







Un polyedre ayant comme face 20 triangles 
20000802 

Sonia pose la question : J'aimerai savoir comment s'appelle un polyedre ayant comme face 20 triangles équilatéraux égaux. Chris Fisher lui répond. 





Maths 
19990111 

Stephane Roissard pose la question : Soit ABC un triangle dans lequel les trois médianes sont de meme longueur. Montrer que ce triangle est quilatéral. Jack LeSage lui répond. 





Question de trigonométrie 
19971211 

JeanPierre Quesnel pose la question : Je suis dans le désert et je parcours 1000 km à partir du point "A" jusqu'au point "B". Si je reviens au point "A" et fais une rotation de 8 degrés en faisant un autre 1000 km, quelle sera la distance en km entre les points "B" et "C". Diane Hanson et Penny Nom lui répond. 





Complementary angles 
20170915 

SM pose la question : The measure of angle A is 60 degrees more than its complement. Find the measure of angle A. Penny Nom lui répond. 





Squares and rectangles 
20170715 

Tront pose la question : So, there's a general rule that all squares are rectangles but not all rectangles are squares. Im trying to find a term that would describe this relationship. I've found that if all of A is B but not all B is A then I'd say that A is a subset of B, but is there a term that describes the relationship as a whole? I don't want to describe the components, I want to describe the relationship as a whole. Penny Nom lui répond. 





An angle and its complement 
20170110 

Ysa pose la question : If the measure of an angle is twice the measure of its complement, what is the measure of the angle? Penny Nom lui répond. 





Hexagonal pyramid bevel angles 
20160930 

Peter pose la question : I have seen your response to a similar question from Steve which Chris and Harley responded to, however I am not familiar with some of the terms. Is there a formula that I can enter my details in which will give me the specific angles I require. The item I am constructing is much larger than the one you responded to previously. Thank you for any assistance you are able to provide. Penny Nom lui répond. 





The number of sides of a polygon 
20160723 

Shriya pose la question : All the angles of a polygon are either 155° or 140°.
There are twice as many angles of 155 °or 140°.
Find the number of sides of the polygon Penny Nom lui répond. 





A congruence theorem for two right angled triangles 
20160717 

Sayari pose la question : Hello.
Is it possible for two right angled triangles to have the same length of base and height and a different hypotenuse? If not so, then why in the congruence criteria RHS the hypotenuse is given more importance? It can also be like 'two triangles are congruent if they are right angled and have the same base and height.'
Thank You. Penny Nom lui répond. 





The difference between the ares of two rectangles 
20160609 

Ingrid pose la question : I am trying to help my son with an area question.
I have the answer, from the solutions, but I cannot figure out how to teach him.
Question:
Two rectangles have lengths 13cm and 19cm respectively.
Their total area is 376cm squared.
If both their widths are whole numbers, what is the difference in their areas?
I know that this is solvable once I determine the widths of the rectangles ,
but how do I go about finding that?
Thanks for your help Chris Fisher and Harley Weston lui répond. 





A trough with a triangular cross section 
20160521 

Clarice pose la question : A trough having an equilateral triangle end sections has sides equal to 0.4 m and 7m long.what is the volume of the liquid in the container if the depth of the water is one half the depth of the trough? Penny Nom lui répond. 





External and interior angles of a regular polygon 
20160419 

pearl pose la question : a polygon has n sides.The exterior angle is 8 times the interior angle
find the value of the interior angle
find the value of n Penny Nom lui répond. 





Angles 
20160312 

Laurynn pose la question : What are angles in general (please include the 'angle of incline')
Thank you
Laurynn Penny Nom lui répond. 





The sum of the angles of a triangle 
20160224 

Sophia pose la question : Does every triangle add up to 180 degrees? (Such as a unique triangle) Penny Nom lui répond. 





The interior and external angles of a regular polygon 
20160217 

percy pose la question : a regular polygon has n sides .The size of each interior angle is eight times the size of each exterior angle .
1.find the size of each exterior angle
2.calculate the value of n Penny Nom lui répond. 





Consecutive angles of a parallelogram 
20160128 

Hanna pose la question : The consecutive angles of a parallelogram measures Penny Nom lui répond. 





The angles of a triangle 
20151217 

Faith pose la question : Does the measure of angle determine the length of its side? For example two angles are congruent then the sides are also congruent because from my understanding the angle determine the shape of triangle. Penny Nom lui répond. 





The measure of an angle in terms of its complement 
20151122 

Pam pose la question : Can you please help me so I can help my daughter the equation is the measure of angle v is 4 time the measure of its complement what is the measure of angle v when the equation is 4x+x=90 Penny Nom lui répond. 





The length of a shadow 
20150801 

maaz pose la question : Hello
I am having trouble with this question:
Lizzie, who is 6 feet tall, stands in her driveway at night, exactly
24 feet from the base of a spotlight, and casts a shadow that is 12
feet long if her friend Hannah who is 5 feet tall decides to stand
next to lizzie how long will her shadow be? Penny Nom lui répond. 





An octagonal frame around a pool 
20150517 

James pose la question : I have a 20' pool and need to put a frame around it using 2by 4 what r the lengths and angle cuts Penny Nom lui répond. 





Cutting a hexagon with a sliding miter saw 
20141123 

Joseph pose la question : I need the angles in degrees for a hexagon one side is 18inches on the outside the problem I am having is in the angle of the cut and I am using a sliding miter saw which only goes from0 degrees to 45 degrees so I need help in getting the angle of the cut Harley Weston lui répond. 





Building an 8 sided box 
20141014 

Michael pose la question : I want to build an 8 sided box. The North, East, South, and West sides I want them to be 4 feet in length.
The NE, SE, SW, and NW sides I want to be 2 feet in length. What angles do I need to cut my angles.
Thanks Michael Penny Nom lui répond. 





Interior angles in a parallelogram 
20140830 

xavier pose la question : so, one of my math homework questions requires me to know how to find out how to find the interior angles in a parallelogram, the question is, "how many interior angles does a parallelogram have?" Penny Nom lui répond. 





A barge of triangular cross section 
20140818 

tushar pose la question : a barge of triangular cross section is 20m long 12 m wide and 6m deep.its floats in SW at a draft if 4m find its displacement Penny Nom lui répond. 





The length of a shadow 
20140509 

vijay pose la question : A girl of height 80 cm is running away from the base of a lamppost at a speed of 2 m/s. If the lamp is 4 m above the ground, find the length of her shadow after 5 seconds. Penny Nom lui répond. 





Two cones 
20140409 

c.j pose la question : what is the length of the radius of the LARGER cone(the LARGER cone has a slant height of 15) when the SMALLER cone has a radius of 8 and a slant height of 12ft ,please help. Penny Nom lui répond. 





Shadows of a father and son 
20140402 

esada pose la question : the father and son cast a shadow of 11 feet and 8 feet,respectively if the son is 4'8'' in height,how tall is the father? Penny Nom lui répond. 





A triangle has angels in the extended ratio of 2:5:8 
20140206 

Rubina pose la question : a triangle has angels in the extended ratio of 2:5:8. find the measure of
all three angles? Penny Nom lui répond. 





Constructing a triangle 
20130822 

Nazrul pose la question : The base, the difference of the angles adjoining the base and the sum of the other
two sides are given. How can I draw the triangle?
Please help me. Chris Fisher lui répond. 





Similar rectangles 
20130817 

Mattie pose la question : The dimensions of a rectangularshaped picture frame are 14 inches long and four inches wide. Which dimensions below represent another frame that i geometrically similar>
a. l=49 in. and w=14in.
b. l=7in and w=3in
c. l=21in and w=8in
d. l=24in and w=14in
thanks Penny Nom lui répond. 





A triangle construction 
20130727 

Nazrul pose la question : Two angles and the difference of the lengths of their opposite sides of a
triangle are given. How can I draw the triangle.
Please help me. Chris Fisher lui répond. 





A kennel for a beagle 
20130603 

david pose la question : Hi, I'm building some beagle kennels and I am in need of help with an angle problem. I need to place a roof on my kennel with a drop of 2inches across 3ft 10inches. the posts on the right side will be 5ft and the post on the left will be 4ft 10in. the posts are 4x4 and the space to be covered is 3ft 10in from the outside of the 4x4. Please help, thanks. Penny Nom lui répond. 





A triangle and an incircle 
20130509 

Max pose la question : On my Geometry Test about tangent, chord, and secant lengths, my teacher gave an extremely difficult problem.
It was a Circle inscribed in a Triangle with all triangle sides being tangents and lengths were given. My class was told to find the length of each segment of the line.
The points on each line were the vertexes of the triangle, and the point where the line hits the circle.
Please explain how someone could do this. Chris Fisher lui répond. 





Drawing a pentagon 
20130506 

jacob pose la question : hello. i am trying to draw a template for a project. but i don't have a
protractor. i'm trying to draw a normal pentagon with 2cm sides. what
i'm trying to figure out is the distance in centimeters from point a, to c,
in a straight line. this is needed so that i can measure and create the
shape without a protractor, and keep the angles and sides correct.
if you can help me with the measurement, or help me another way,
any help would be greatly appreciated. thank you. Penny Nom lui répond. 





Trigonometry 
20130323 

Tizoc pose la question : I am in a trig class and I have a conflict. When solving the length of a side, I know what trig function to use, but I do not know what angle to use in a calculator. To make this a little more understandable, if I have all the angles available in a right triangle and I use the tangent function, how do I know what to use?
Heres what I do not know what to put in my calculator: Tan(?)
Thanks in Advance! Penny Nom lui répond. 





Three right triangles 
20120726 

Jora pose la question : I am having a lot of difficulties with this question.
Name: Jora
Subject: Math
Who are you: Student Chris Fisher lui répond. 





An octagonal sandbox around a pool 
20120612 

Linda pose la question : My pool is 15 feet across and it is round.
How do I measure to cut wood to build a sandbox around it? was thinking it will look like an octagon.
Thanks Harley Weston lui répond. 





Squares and triangles 
20111206 

Liaqath pose la question : You have squares and triangles.
Altogether there are 33 sides.
How many squares do you have?
How many triangles do you have? Penny Nom lui répond. 





Solve for theta if 8cos^2 theta3=1 
20111202 

Katherine pose la question : Hi,
I have just learned to solve trigonometric problems for theta and have one specific question in order to find the solutions to my homework.
I will use one example for this question. If I have 8cos^2 theta3=1
I first divide by 8 and get cos^2theta=3/8
then I have cos theta= plus or minus the square root of 3/8
Then I assume that I plug in inverse cos (the square root of 3/8) to my calculator.
How do I find the four solutions (we are typically supposed to find four, I believe?)
Can you help me with finding the solution to this problem? Thank you! Penny Nom lui répond. 





A right angled triangle 
20111031 

bijo pose la question : how can i find the tangent point at a circle with origin as center with radius r and the tangent pass through a given point P? I also want to find out the third point of a right angled triangle given other two points? Chris Fisher lui répond. 





Building a custom range hood 
20111008 

Bill pose la question : I'm building a custom range hood for a customer with special order material that matches
their newly installed cabinets and I need it to be perfect. The hood is basically a pyramid
but the 4th side is the flat wall at the back and a flat, rectangular top. I need to calculate
the bevel and miter of the three sides but I never was very good with geometry functions
(although I am fairly good with other math fields). I either need the calculations from you
at least (shudder) a formula or set of formulas so that I can calculate them myself. Harley Weston lui répond. 





Dividing a polygon into triangles 
20110416 

Foxie pose la question : You have a given regular polygon with n vertices and you divide it into triangles(using the vertices of the polygon) which each share at least one side with the polygon. How many distinct ways can you divide the polygon if its vertices are numbered? For n=3 it's 1 way, for n=4 it's 2 ways for n=5 5 ways, I'm not quite sure but think that for n=6 it's 12 ways... thanks in advance! Claude Tardif lui répond. 





The interior angles of a pentagon 
20110310 

Daima pose la question : I need help!
The interior angle of a pentagon i s5 ( I hope ) or 540 degrees.
The interior angle of a pentagon is what? Explain to me please.
Daima Penny Nom lui répond. 





Triangles with perimeter 16 cm 
20110222 

Chong pose la question : How many triangles (up yo congruence) with perimeter 16 cm and whose lengths of its side are integers? Chris Fisher lui répond. 





Calibrating a conical tank 
20110205 

Bill pose la question : Hi, I have a round tank with tapered sides where I know the diameter at the top and bottom. Is there a formula I can use to calculate the volume by measuring from the bottom up the side (at the angle of the side) to any given point? Thanks, Bill Stephen La Rocque and Penny Nom lui répond. 





The height of a lamp 
20110113 

Dorothy pose la question : I need to find the lamp height with casting shadow (base line of triangle where a boy 1.6m tall stands 3m from base of street lamp and has a 2m shadow. In other words, think of a right angle triangle with zero height starting at left, then 2m to right stands boy (1.6m high). Angle (hypotenuse) increases up to top of street lamp with 'x' height and 3m base. Penny Nom lui répond. 





Draw a figure with 16 triangles using only 6 line segements 
20101216 

Jill pose la question : How can you draw a figure with 16 triangles using only 6 line segements? Stephen La Rocque lui répond. 





The angles in an mgon and genrealizations 
20101016 

Michael pose la question : Hello:
In answer to a student's question, someone named Penny from
your organization provided a proof that the sum of the interior
angles of a triangle in the plane is pi radians (or 180 degrees).
I am interested (and I'm sure many other people would be too) in
3 potential generalizations of this basic fact in plane geometry: Walter Whiteley lui répond. 





A spaceship playhouse 
20100726 

Dave pose la question : I would like to build a spaceship playhouse for my grandson I want it to
be about 36" around and I want to use 5/4 decking boards that measure
5 1/2" wide how do I figure out how to lay out a base pattern to nail to
(what angle do I need to cut and how many boards will it take to go around
the circle. Penny Nom lui répond. 





An octagon shaped bench 
20100709 

rob pose la question : i am trying to build a octagon shaped bench to fit inside a 69 inch round hot tub so that the tip of each point touches the edge of the circle where it will be fastened. Stephen La Rocque lui répond. 





Rays and angles 
20100624 

cristina pose la question : what is the formula for finding the number of angels that can be named by a given number of rays with the same endpoint? Robert Dawson lui répond. 





An angle in a triangle 
20100506 

Morgan pose la question : Question from Morgan, a student:
t
8 t t 8
t 78 t
t t
t t
t x t
ttttttttttttttttttttttttt
10
I'm having trouble solving for x I'm not sure where to start ( the ones in the middle of the triangle are both degrees) thanks in advance for your help i really do appreciate it Penny Nom lui répond. 





A wishing well 
20100504 

Cassie pose la question : I'm trying to construct a Wishing Well made of treated 2x4 wood, so the actual measurement is 3 1/2 by 1 1/2. The well is going to be three feet in diameter. I'm trying to construct this as circular as possible, what angle should the wood panels be cut at? Penny Nom lui répond. 





An irregular octagon 
20100309 

Gayle pose la question : Question from Gayle:
I am building an irregular shaped octagon wooden box.
The measurements are 291/2 inches by 211/2 inches.
Sides are 12 inches.
It will be 36 inches high.
What would the cutting angles degrees be? Harley Weston lui répond. 





How many triangles...? 
20100222 

deciree pose la question : Given 12 points, no 3 of them on a line with 6 red, 4 blue and 2 green points.
a) How many triangles have vertices all the same color?
b)How many triangles have vertices with each vertex a different color?
c)How many triangles have at least one green vertex?
thanks to lorraine! Penny Nom lui répond. 





Triangles 
20100219 

Wiliam pose la question : A box contains one 2 inch rod, one 3 inch rod, one 4 inch, and one 5 inch rod.
What is the maximum number of different triangles that can be made using these rods as sides? Penny Nom lui répond. 





Triangles on a base of 2.4 meters 
20091226 

Allan pose la question : Please,How do I calculate the height of a triangle when I only know the width of the base line,It is 2.4 mtrs. Thankyou very much. Penny Nom lui répond. 





Polygons, diagonals and the sum of the measures of the angles 
20091218 

jason pose la question : find the set of polygons in which the number of diagonals is greater than the sum of the measures of the angles Robert Dawson lui répond. 





The line through D(4, 0) and E(2, 6) 
20091116 

Rogerson pose la question : The point F is on the line through D(4, 0) and E(2, 6) so that DF=4DE. Find the coordinates of F. Penny Nom lui répond. 





The three angles of a triangle 
20091013 

Michelle pose la question : The second angle of a triangular garden is four times as large as the first.
The third angle is 45 less than the sum of the other two angles.
Find the measure of the other two angles? Penny Nom lui répond. 





Two rectangles 
20091008 

Lillian pose la question : A rectangle is 5cm longer than twice its width.
The width of another rectangle is 3cm less
than the width of the first rectangle and its length is 6cm more than 3 times its
width. If the perimeters are equal, find the dimensions of both rectangles Penny Nom lui répond. 





The maximum number of right angles in a polygon 
20091005 

Bruce pose la question : Is there way other than by trial and error drawing to determine the maximum number of right angles in a polygon? Secondary question would be maximum number of right angles in a CONVEX polygon. Is there a mathematical way to look at this for both convex and concave polygons? Or are we limited to trial and error drawing? Chris Fisher lui répond. 





A paper towel roll 
20090819 

Jeff pose la question : I am making a spiral tube with paper that is 2" in dia. and 102" long
I will be using paper that is slit 3" wide how many lineal feet of paper will
I need to to cover the 102"
I will be using 3 rolls of paper that will over lap the other by half to make
a hard tube (paper core) in a roll of paper towels
Thanks Jeff Penny Nom lui répond. 





How can I trisect an angle? 
20090727 

Nazrul pose la question : How can I trisect an angle? Robert Dawson lui répond. 





The position of the fulcrum 
20090523 

jim pose la question : I think I need a formula. I need to know how far an object will be lifted.
A beam is 246 inches long on one side of the fulcrum, and 41 inches on the other side,
if I push down 36 inches on the long side of the beam, how much will the short side move up? Stephen La Rocque lui répond. 





The sum of the angles of a triangle 
20090518 

mary pose la question : prove that the sum of the three angles inside any triangle always add up to 180 degrees? Harley Weston lui répond. 





Angles in a triangle 
20090516 

Robert pose la question : The second angle of a triangle is twice the sizee of the first angle, the third angle is 48 degrees less than the sum of the other two angles. What are the measurements of all 3 angles?
PS: please help Stephen La Rocque lui répond. 





The hypotenuse of a right angled triangle 
20090511 

Deb pose la question : Find the length of the hypotenuse of a right angled triangle with one leg 7 cm longer than the other and the hypotenuse 2 cm longer than the longer leg. I've ended up with the hypotenuse = x+9, another side = x and the other side = x+7. what do i do next? Penny Nom lui répond. 





The interior angles of a pentagon 
20090420 

Mary pose la question : If four interior angles of a fivesided figure pentagon measure 100 degrees each, what will the fifth angle measure? Harley Weston lui répond. 





Two similar rectangles 
20090419 

Alyssa pose la question : The ratio of the lengths of corresponding sides of two similar rectangles is 3:5. the small rectangle has an area of 36 square centimeters. What is the are of the large rectangle? Penny Nom lui répond. 





The angles of a triangle 
20090311 

Marissa pose la question : The angles in a triangle measure 7x1, 18x+2, and 5x+10. Determine whether the
triangle is acute, obtuse, or right. State your reasons clearly. Robert Dawson lui répond. 





Triangles within triangles 
20090224 

Mari pose la question : a large shaded triangle changes each day with a white triangle appearing
in the center of each shaded one. If this pattern continues, how many white
triangles will be there on the 6th day? On the 6th day, what fraction of
the large outer triangle will be white?THANKS! Robert Dawson lui répond. 





Trig functions without geometric data 
20090224 

bob pose la question : I do not understand how it is possible to find the sine, cosine, or tangent of an angle if
there is no hypotenuse, opposite or adjacent side?! Robert Dawson lui répond. 





Forming an arc with 2 inch steel 
20090211 

Craige pose la question : I need to calculate the bending radius of 2" wide steel to achieve given inside and outside arc lengths Harley Weston lui répond. 





A 306090 triangle 
20090203 

Inez pose la question : If you have a 306090 triangle and the only side you get is 73 and a 90 degree box, how do you find the area? Penny Nom lui répond. 





The ratio of the measures of the three angles of a triangle 
20090118 

mary pose la question : The ratio of the measures of the three angles of a triangle is 2:5:8. What is the measure of each angle of the triangle? Robert Dawson and Harley Weston lui répond. 





A stack of rectangles 
20090111 

ashwani pose la question : Could you please advise the area of a rectangles pyramid.
There are 5 rectangles placed one above the other. The top most rectangle has length 2 cm and height 2 cm. The subsequent rectangles length is increased by 1 cm on both the sides, while the height of the 2nd and 3rd rectangle is 2cm each, while the 4th & 5th has a height of 3 cm each. Could you please let me know the the area of the figure and the formula to calculate Penny Nom lui répond. 





A flattopped pyramid 
20090110 

Tom pose la question : I am planning to build an open ended, flattopped pyramid with a
rectangular base 28 x 36 in.; a square top 6 x6 in.; and a vertical
height of 16 in.
I know how to calculate the dimensions of each of the pyramid sides but
I don't know how to calculate the interior angles when I bend the sheet
metal. I will cut the four sides separately and add a one inch flange
to each "vertical" edge of the two larger sides to allow for
a bonding surface for the assembly. How do I calculate that angle? I
know it will be greater than 90 degrees but by how much? Harley Weston lui répond. 





Two angles are supplementary 
20090108 

Stephanie pose la question : two angles are supplementary, one of the angles is 30 degrees more than double the other angle.
find the first angle, the second angle the complement of the given angle. Robert Dawson lui répond. 





Pouring angles for a crucible 
20081220 

Richard pose la question : I am trying to work at pouring angles and volume left in during pouring a crucible, The crucible is cylindrical and flat bottomed.
I know the diameter, radius and volume of the crucibles. and the volume of liquid going into it.
So lets say the crucible is only half full firstly I need to work out the angle just before its going to pour. ( I can work this out as long as there is a certain volume of liquid if its not enough I cant do it)
Now the problem I also need to work out how much I should tilt the crucible to allow a certain amount out and be able to do this untill the volume reaches 0 at 90' turn. This is where I am stuck.
The reason for needing to be able to work this out is so i can develop a constant flow for example 10Kg of metal per second.
Thank you very much for you time Harley Weston lui répond. 





The volume of a feed hopper 
20081218 

John pose la question : I need to calculate the volume of a feed hopper, and I'm not sure how to break it down. The top of the hopper is 36" x 36", it is 30" deep, and ends at a 6" x 6" plate. One side of the hopper is straight top to bottom, of course tapering on two sides to meet at the plate. The other three sides angle down at about 75 degrees. I need to determine the cubic foot volume of this hopper (it is used for ground coffee) so I can configure a vibrator to knock down residual grounds. Thanks. Robert Dawson lui répond. 





3 equidistant points 
20081201 

Damien pose la question : How do you find 3 equidistant points (C,D,E) on a line between point A(Xa, Ya) and point B(Xb, Yb) so that AC, CD, DE and EB are all equal? Chris Fisher lui répond. 





The midpoint o a line segment 
20081115 

Jane pose la question : The vertices of a triangle are at (1,7), (6,1) and (0,3). Find the coordinates of the midpoints of the sides. Penny Nom lui répond. 





The angles and sides of a triangle 
20081113 

JAMIE pose la question : a triangle with a side(b)37m an angle(C)70degrees and (a)79m find values of angles A and B and length of side c Stephen La Rocque lui répond. 





Supplementary angles 
20081110 

Anna pose la question : <A and <B are supplementary angles. Twice the measure of <B is onefourth the measure of <A. Find the measure of both angles. Penny Nom lui répond. 





A flagpole and a yardstick 
20081107 

Wanda pose la question : One boy holds a yardstick vertically at a point 40 feet from the base of the flagpole. The other boy backs away from the pole to a point where he sights the top of the pole over the top of the yardstick. If his position is 1 ft 9 in from the yardstick and his eye level is 2 ft above the ground, find the height of the flagpole. Penny Nom lui répond. 





The angles of a triangle 
20081031 

kyla pose la question : an isosceles triangle has two 50 degrees angles.what is the measure of the third angle? explain how you found your answer. Penny Nom lui répond. 





Three congruent rectangles 
20081027 

Meagan pose la question : Here is my problem: Three congruent (nonsquare) rectangles are placed
to form a larger rectangle. [Two are oriented the same way and the
"stacked" while the third is rotated 90 degrees and placed next to the
other two.] The total area is 1350 square cetimeters. Square ABCD is
then created that has the same perimeter as the large rectangle that was
created. E is the midpoint of line CD and F is the midpoint of BC. Find the
area of triangle AEF. Penny Nom lui répond. 





Octagon angles 
20081006 

John pose la question : My daughter wants to build an octagon using PVC pipe fittings. There are several pipe "elbows" available, including 45 degree. I'm trying to determine if if an octagon can be constructed by using 8 pairs of 45 degree elbows, connected to each other by 8 sections of straight pipe of some equal legnth. This makes sense to me intiutively, but I do not know how this can be properly expressed in geometric terms. Chris Fisher, Victoria West and Harley Weston lui répond. 





Supplementary angles 
20080911 

Shanaz pose la question : Find an angle such that 3 times its supplement equals 450. Penny Nom lui répond. 





Number of angles formed by rays 
20080829 

Shon pose la question : what is the formula for finding the number of angels that can be named by a given number of rays with the same endpoint? Stephen La Rocque lui répond. 





Angles in an octagon 
20080826 

Arvie pose la question : I have seen your answer to Kay on how she can find the length for the sides of an octagon for a 4 foot window, but what is the angle that will need to be cut to get to 4 feet Penny Nom lui répond. 





Joining vertices in a polygon 
20080818 

Megan pose la question : I'm trying to develop a relationship between the number of points of a regular polygon and the
(a) number of lines you could draw between those points,
(b) number of triangles you could draw,
(c) number of quadrilaterals,
etc. Penny Nom lui répond. 





Similar Triangles Given a Median 
20080817 

RAM pose la question : Sides AB , AC and median AD of a triangle ABC are respectively proportional to
PQ PR and median PM of another triangle PQR. Show that ABC is similar to PQR Janice Cotcher lui répond. 





Similar triangles 
20080812 

ramarao pose la question : D is a point on side BC of a triangle ABC such that BD/CD=AB/AC. prove that AD is the bisector
AD is the bisector of BAC Chris Fisher lui répond. 





Angles in a regular tetrahedron 
20080807 

Carla pose la question : Hi guys,
A regular tetrahedron has all its edges 8cm in length.
Find the angles which an edge makes with the base.
Thanks.
Carla Penny Nom lui répond. 





The angle between two faces of a pyramid 
20080806 

Carla pose la question : A pyramid has its vertex directly above the centre of its square base.
The edges of the base are each 6cm, and the vertical height is 8cm.
Find the angle between 2 adjacent slant faces. Penny Nom lui répond. 





Some angles in a pyramid 
20080804 

Carla pose la question : A symmetrical pyramid stands on a square base of side 8cm. The slant height of
the pyramidis 20cm. Find the angle between the slant edge and the base, and the angle between
a slant face and the base. Penny Nom lui répond. 





Hexadecagon 
20080709 

Dave pose la question : I would like to know at what length and angle I would cut wood to make a Hexadecagon. Penny Nom lui répond. 





Fit 7 different rectangles on grid paper 
20080702 

anonomous pose la question : I need to fit 7 different rectangles on grid paper of 1cm squared.
Each squared centimetre equals 4 squared metres, and it needs to end up as area 64 square metres. Janice Cotcher lui répond. 





The exterior angles of a polygon 
20080626 

evelina pose la question : how many sides has a regular polygon if the measures of the exterior angle is given Walter Whiteley lui répond. 





sin(2x)/sin(3x) 
20080619 

matt pose la question : how does sin2x break down (not with identities) and how would sin3x be created. My
prob. is sin 2x/ sin 3x and I want to know how the double(or triple angle) would break
down. I want to be able to cancel out sins. Thanks! Harley Weston lui répond. 





The angles of a parallelogram 
20080611 

light pose la question : ABCD is a parallelogram. If angle A. = (4x=17)degrees and angle B. = (3x5)degrees , what is angle c? Penny Nom lui répond. 





The two acute angles in a right triangle 
20080605 

Crystal pose la question : In the right triangle the ratio of the measure of the two acute angles is 4:1. What is the measure in degrees of the larger acute angle? Penny Nom lui répond. 





The interior angles of an 18sided polygon 
20080604 

Alfred pose la question : How do I find the sum of the interior angles of an 18sided polygon? Janice Cotcher lui répond. 





The angles of an irregular pentagon 
20080520 

victoria pose la question : The sum of the measure of two angles is 240. If the remaining angles are congruent, what is the measure of each angle? Penny Nom lui répond. 





The Pythagorean theorem with triangles rather than squares 
20080429 

Zachary pose la question : I need to figure out how to prove the pythagorean theoorem using equilateral triangles
instead of using square. I know that A^2+B^2=C^2, but how do you get that by using equilateral
triangles. I know the area of a triangle is BH1/2=Area. So what i need to know is how to derieve the
formula of a triangle to get the pythagorean theorem Penny Nom lui répond. 





Side lengths and angles in a regular octagon 
20080409 

Lori pose la question : I am a builder and need to find the length of the sides of an octagon. I know the length between
the parallel sides (26 feet). What is the length of each side? What is the angle measurement? Harley Weston lui répond. 





A fish tank in the shape of an irregular pentagon 
20080329 

richie pose la question : i am building a fish tank. it is going to be an irregular pentagon. the sides are going to be
24"
24"
8"
8"
32"(approximately)
there will 3 right angles A, B, E
my question is how to figure out the degree of the angles that are not right angles (C,D)? Chris Fisher lui répond. 





Similar triangles 
20080326 

Nisha pose la question : In triangle ABC, LM is parallel to AB. If AL=x3,AC=2x,BM=x2,BC=2x=3. Find x Penny Nom lui répond. 





A word problem about a triangle 
20080323 

kathy pose la question : The measure of the largest angle of a triangle is twice the measure of the second largest. The measure of the second largest is 20 degrees more than the measure of the smallest. Find the measure of each angle. Melanie Tyrer lui répond. 





Angles subtended by the same arc 
20080323 

Reid pose la question : Prove that two inscribed angles subtended by the same arc are equal. Stephen La Rocque lui répond. 





A 6 pointed star 
20080304 

Siddharth pose la question : When 2 congruent equilateral triangles share a common center, their union can be a star
If their overlap is a regular hexagon with an area of 60, what is the area of one of the original equilateral triangles?
a) 60 b) 70 c) 80 d)90 e)100 Stephen La Rocque lui répond. 





The angles of a triangle 
20080301 

Allen pose la question : How to find the other two angles of a scalene triangle if one angle is given Steve La Rocque and Penny Nom lui répond. 





Two right triangles 
20080218 

Amy pose la question : Hi, I have a problem that has me stumped.
There are two right triangles that share the same adjacent side (AB) which
is 240'. The right angles of each triangle are at the opposite ends of the
shared side.
The Opposite side (AC) of Triangle ABC is 180'
and the Hypotenuse (CB) is 300'.
The Opposite side (BD) of Triangle ABD is 100'
and the Hypotenuse (AD) is 260'.
How do I figure out where the hypotenuses intersect? Stephen La Rocque and Harley Weston lui répond. 





A flagpole and a statue 
20080209 

Krista pose la question : A flagpole casts a ten meter (m) shadow at the same time as a six metre (m) statute beside it casts a two metre shadow. What is the height of the flagpole?? Steve La Rocque and Penny Nom lui répond. 





The interior angles of a parallelogram 
20080129 

amber pose la question : the measure of one interior angle of a parallelogram is 42 degrees more than twice the measure of another angle. Find the measure of each angle. Penny Nom lui répond. 





The interior angles of a parallelogram 
20080128 

steffie pose la question : How do you calculate the interior angle sof a parallelogram? Penny Nom lui répond. 





The three angles of a triangle 
20080121 

val pose la question : two angle in a triangle equal 120 degree. what is the measure of the third angle? Penny Nom lui répond. 





The angles of a triangle given the three sides 
20080117 

Lucy pose la question : Is there a way to find the angles of a triangle just by knowing the lengths of it's sides?
It seems like the would be a relationship between the two, but I'm not sure. Stephen La Rocque and Harley Weston lui répond. 





Forces on an inclined plane 
20080110 

Ron pose la question : A body that weighs 540lbs is caused to slide up an inclined plane with a uniform velocity by a force that acts parallel to the plane. For each foot of horizontal distance, there is a vertical rise of 2in. If the coefficient of sliding friction is 0.16, what force is required to move the body? Stephen La Rocque lui répond. 





Lining up coins visually using geometry and trigonometry 
20071231 

Jessica pose la question : a) In what order would you arrange a penny, a nickel, a dime, a quarter, and a halfdollar so that they all have the same apparent size? The diameters of the coins, in thousandths of inches, are as follows: penny, 750; nickel, 835; dime, 705; quarter, 955; halfdollar, 1205.
b) How should the coins be placed, if the distance between the dime and the halfdollar is 100 units?
How far from thw dime should your eye be to see that all the coins have the same apparent size?
c) What angle do the coins subtend when they have the same apparent size? Stephen La Rocque lui répond. 





How many triangles can be formed? 
20071221 

pankaj pose la question : Q.There is 2 lines parallel to each other. If 1st has 5 points in it and 2nd 3 points in it,how many triangles can be formed? Penny Nom lui répond. 





Smallest cone containing a 4cm radius inscribed sphere 
20071219 

Eva pose la question : A sphere with a radius of 4cm is inscribed into a cone. Find the minimum volume of the cone. Stephen La Rocque lui répond. 





Finding all the angles 
20071213 

Rajesh pose la question : An eqilateral triangle is drawn in a square with one of the side as its base and draw the lines from the other angular sides such that there are four triangles
formed inside the square which includes the equilateral triangle.I want to know all the angles of all the triangles formed inside the square. Stephen La Rocque and Penny Nom lui répond. 





What angle should he turn? 
20071201 

Jasmine pose la question : Bob is traveling due north he then turns left 45 degrees followed by four 20 degree turns to the right
What is his new heading if he needed to turn so his heading was SSW what direction and what angle should he turn? Walter Whiteley lui répond. 





Related Rates (streetlamp and shadow) 
20071109 

Casey pose la question : A street light is mounted at the top of a 15ft pole. A man 6ft tall walks away from the pole at a rate of 5ft per second. How fast is the tip of his shadow moving when he is 40ft from the pole? Stephen La Rocque and Penny Nom lui répond. 





Two triangles 
20071108 

Barbara pose la question : If the base of a larger triangle is 34 inches long, what is the length of side A of the smaller triangle?
(the small triangle has on top the letter a on the right side of the triangle it has the letter b, and at the bottom of the small triangle it has the number 17) Penny Nom lui répond. 





Two mirrors 
20071024 

Peter pose la question : The reflecting surfaces of two intersecting flat mirrors are at an angle θ (0° < θ < 90°). For a light ray that strikes the horizontal mirror, show that the emerging ray will intersect the incident ray at an angle β = 180° – 2θ. Stephen La Rocque lui répond. 





Given a six by six square, how rectangles are there in the square? 
20071024 

Maria pose la question : Given a six by six square, how rectangles are there in the square? Stephen La Rocque lui répond. 





Surface area of an openended cone 
20071016 

Lorne pose la question : What is the surface area of an open ended cone? Measured at 10' high,
16' diameter on the bottom and 2' diameter at the top. Stephen La Rocque lui répond. 





The angles in a polygon 
20071011 

Farzan pose la question : Prove with induction that in a polygon( that may not be convex )
with n sides, the sum of the amounts of the angles become 180(n2).
If there is any easier methods to prove the problem, please write as well. Stephen La Rocque lui répond. 





Finding equations, intersection point of two lines at right angles 
20070922 

Yaz pose la question : Find the equation of the line joining A(1,9) to B(6,120). Another line passes through C(7,5) and meets AB at rigth angle of D. Find the euation of CD and calculate the coordinates of D. Stephen La Rocque lui répond. 





Composite angles 
20070913 

Gilbert pose la question : what is a composite angle? please help Stephen La Rocque lui répond. 





Similar triangles 
20070829 

James pose la question : Question: In the triangle ABC, X is a point on AC. AX = 15 m and XC = 5 m. The angle AXB is 60 degrees and the angle ABC is 120 degrees. Find the length of BC.
I am sure to an extent that this has to do with similar triangles, but I am not certain. Harley Weston lui répond. 





Reference angles 
20070825 

Jenny pose la question : find the reference angles for the angles given below, find the quadrants in which the angles lie
1. 0=6n/7
2. 0=3.3 Stephen La Rocque lui répond. 





Finding the radius of an inscribed circle 
20070705 

Maria pose la question : I need to find the radius of a circle which is inscribed inside an obtuse triangle ABC. I know all the angles and all the lengths of the triangle. Stephen La Rocque and Chris Fisher lui répond. 





Volume in a triangular water trough 
20070624 

David pose la question : A water trough has sloping sides of length 500mm making it triangular in cross section, with vertical ends. The width at the top is 600mm and the length is 2.0 metres.
(i) Calculate the capacity of the trough, giving your answer accurate to the nearest litre.
(ii) Find out the depth of the water when the trough is half full. Stephen La Rocque lui répond. 





The sum of angles in a square is three hundred and sixty degrees 
20070621 

victor pose la question : can you please send to me a formalize proof for the assertion that, the sum of angles in a square is three hundred and sixty degrees. i will be grateful to hear from you Stephen La Rocque lui répond. 





How can I find out how many sides there are? 
20070423 

gn pose la question : I know the angle measurements of a convex polygon. They are congruent angles. How can I find out how many sides there are? Steve La Rocque, Penny Nom and Walter Whiteley lui répond. 





Interior and exterior angles 
20070402 

Anuj pose la question : If in a regular polygon, each exterior angle is twice the interior angle,find the number of sides? Leeanne Boehm lui répond. 





Find the measure of all 3 angles. 
20070328 

Brittney pose la question : The smallest angle in a triangle is onethird of the largest angle. The third angle is 10 more than the smallest one. Find the measure of all 3 angles. Stephen La Rocque lui répond. 





The height of a pole 
20070322 

clyde pose la question : I am trying to determine the height of a pole by using 3 angles top 30.8 deg, center 17.3 deg, and bottom 5.8 deg. Can you point me in the right direction ? Stephen La Rocque lui répond. 





Similar triangles 
20070221 

Vivienne pose la question : The lengths of the sides of a triangle are 8, 15, & 17. If the longest side of a simlar triangle is 51, what is the length of the shortest side? Stephen La Rocque and Penny Nom lui répond. 





The interior angles of a parallelogram 
20070207 

jenniffeir pose la question : Can a parallelogram have two 45 degree angles and two 75 degree angles? Haley Ess lui répond. 





Angle of elevation 
20070205 

Zee pose la question : A 55 ft. flagpole casts a 25 ft. shadow. Calculate the angle of elevation to the sun to the nearest degree. Stephen La Rocque lui répond. 





Height of a right triangle? 
20070129 

Engelbert pose la question : The base of the right triangle is 50 ft. At the angle (on the base of the triangle) across from the right angle is labeled portion (a triangle within a triangle), the base of this little triangle is 10 ft. and the height is 6 ft. What equation can i use to solve this? Steve La Rocque and Haley Ess lui répond. 





In the shadow of a building 
20070111 

Bill pose la question : if a building b feet cast a shadow f feet long, then, at the same time of the day, a tree t feet high will cast a shadow, how many feet long? Stephen La Rocque lui répond. 





Are all rectangles trapezoids? 
20070105 

Sarah pose la question : Are all rectangles trapezoids? Chris Fisher lui répond. 





How do the perimeters of the two pentagons compare? 
20070102 

Robert pose la question : If the area of one pentagon is eightyone times the area of another pentagon, how do the perimeters of the two pentagons compare? Penny Nom lui répond. 





An octagonal birdhouse 
20061230 

Verner pose la question : I am building a octagon birdhouse,what degree would I cut each side of each piece of wood to assemble the birdhouse? Penny Nom lui répond. 





The sum of the angles in a triangle 
20061212 

Becky pose la question : Why does a triangle always equal 180 degrees? We know that all the angles add up to 180 degrees but cant find a valid reason for it. Penny Nom lui répond. 





The height of a building 
20061119 

Sweetie pose la question : I have to figure out the measure of the water towers antenna on my schools campus using up to two items created by me and a manual. I don't know far away we are going to have to be. I need to have a fool proof way to figure out the distance to the tower. I have an idea using trigonometry but its really roughly estimated. Do you have any suggestions? Stephen La Rocque lui répond. 





An equilateral triangle has been wedged in between two circles. 
20060922 

Kim pose la question :
An equilateral triangle has been wedged in between two circles. How does the diameter of the smaller circle compare to the diameter of the larger circle.
image: circle inside of an equilateral triangle touching all sides of the triangle; both the triangle and the circle inside are placed into a larger circle where the triangle vertices all touch the circle
Penny Nom lui répond. 





The length of 2 sides of a triangle 
20060915 

Lonnie pose la question : I need to know how to figure the length of 2 sides of a triangle, as the following example:
The length of the bottom is 12' and the angles are 45, 45 I need to know how long the other 2 sides must be to get an angle of 90 at the top. Stephen La Rocque lui répond. 





How high (in feet) is the mountain? 
20060829 

Briana pose la question : A survey team is trying to estimate the height of a mountain above a level plain. From one point on the plain, they observe that the angle of elevation to the top of the mountain is 29 degrees. From a point 2000 feet closer to the mountain along the plain, they find that the angle of elevation is 31 degrees.
How high (in feet) is the mountain? Stephen La Rocque lui répond. 





Mini Golf 
20060817 

Sarah pose la question : I am a sixth grade teacher in Minnesota. I want to have my students explore mini golf and calculate the reflections and angles so that they can figure out how to hit a hole in one. I know that my daughter had various problems like this in eighth grade geometry, but I can't seem to find any internet activities of the appropriate level. Stephen La Rocque lui répond. 





An angle in a parallelogram 
20060813 

Sam pose la question : Parallelogram ABCD has diagonal AC equal in length to side AB. CD is produced to E so that D is between E and C. If angle BAC =30 degrees find the size of angle ADE. Stephen La Rocque lui répond. 





How fast is the water level rising 
20060812 

Erin pose la question : Water runs into a conical tank at the rate of 9ft^{3}/min. The tank stands point down and has a height of 10 ft. and a base radius of 5 ft. How fast is the water level rising when the water is 6 ft. deep? (V=1/3 pi r^{2} h). Penny Nom lui répond. 





Designing a garage 
20060608 

A builder pose la question : I'm currently designing a garage and came upon this interesting math problem. I've tried using various methods to solve it but have so far been unsuccessful. I've included a picture as its far easier to show you my question than explain it verbally. I realize it could be done by trial and error but i'm looking for a real solution. Stephen La Rocque and Penny Nom lui répond. 





What is the measure of the interior angles of a decagon? 
20060510 

Malissa pose la question : What is the measure of the interior angles of a decagon?
And what is the measure of each interior angle of a regular decagon? Stephen La Rocque lui répond. 





Finding the supplementary angles 
20060422 

Kendra pose la question : Angles ABC and DBA are supplementary. If m Stephen La Rocque lui répond. 





Solve the equation cos x = sin 20 where x is acute. 
20060326 

Elle pose la question : Solve the equation cos x = sin 20 where x is acute. Stephen La Rocque lui répond. 





The volume of water in a cone 
20060321 

Ghulam pose la question : A vessel has the shape of an inverted cone.The radius of the top is 8 cm and the height is 20 cm. Water is poured in to a height of x cm.Show that if the volume of the water is V cubic cm,then V=(4/75)pi x3. Penny Nom lui répond. 





Heights and shadows 
20060306 

Debra pose la question : A person is 7 ft tall and his shadow is 10 ft tall. using the same info what is the shadow of a person who is 5ft tall
Stephen La Rocque lui répond. 





How do you find the angles in a triangle? 
20060127 

Keith pose la question : How do you find the angles in a triangle if you know the lengths of the sides? Chris Fisher and Penny Nom lui répond. 





Subdividing a polygon into triangles 
20060126 

Adam pose la question : is there an algorithm to divide a regular polygon into N
equilateral triangles having the same area (no limit on N), or if not, an
algorithm to divide a regular polygon into N triangles having the same shape
and size? Chris Fisher lui répond. 





The third side of a triangle 
20060125 

Bob pose la question : Is there any way to obtain the third side of a triangle when 2 sides are the same length (2.18 inches). I also need to find the angles. Penny Nom lui répond. 





Right angles 
20060125 

AshLee pose la question : I was recently given a challenge in my Algebra class. My teacher wanted to know about a right angle. He said he would give five bonus points to the person that could bring in information. (I know five bonus points may not seem like a lot but in this class, they are.) I looked on this site and I found out why it was called a right triangle, but my teacher want to know where did that theory come from. I was wondering too... not just because of the bonus points. Penny Nom lui répond. 





The three angles in a triangle 
20060123 

A student pose la question : the measure of the 2nd angle in a triangle is 4 more than the measure of the 1st angle. the measure of the 3rd angle is eight more than twice the measure of the 1st angle. find the measure of each angle. Penny Nom lui répond. 





The angles in a hexagon 
20060122 

Linda pose la question : My problem is in relation to wood and making a six sided object from it. On my saw, there is a place to set the angle to which you wish to cut. I cannot for the life of me, figure this out. I am starting with a piece of plywood (1/4" x 6" x 18") and need to know what the angle degree would be to make each of the sides match perfectly to form a hexagon. Trial and error just is not working. Can someone help me? Penny Nom lui répond. 





Interior and external angles of a polygon 
20060117 

Anthony pose la question :
In a regular polygon, the ratio of the interior angles to the exterior angles is 3:1.
(a) Find the measure of the interior angle.
(b) How many sides are there
Penny Nom lui répond. 





The sum of the angels in a triangle 
20051125 

Rachel pose la question : how do you prove, without knowing any of the measurements or degrees, that the three angles of a triangle equal 180? what are the steps for proving that? Penny Nom lui répond. 





Find the measure of each angle 
20051125 

Bev pose la question : in triangle abc, angle a is four times as large as angle b, angle c measures 20 degrees less than angle b. find the measure of each angle. Penny Nom lui répond. 





The height of a tower 
20051108 

Vinita pose la question : Observers at point A and B, who Stand on level ground on opposite sides of a tower, measure the angle of elevation to the top of the tower to be 33 degrees and 49 degrees respectively. Another point C is 120 m from point B, Triangle ABC =67 degrees and BAC = 31 degrees. Find the height of the tower to the nearest metre. Penny Nom lui répond. 





Triangles with integer sides 
20051104 

Tammy pose la question : I am trying to find another pair of integer sided isosceles triangles, not the same as the ones listed below, with equal areas.
(5,5,8)
(5,5,6) Chri Fisher lui répond. 





What is the sum of the measures of the angles of a decagon? 
20051015 

Dianna pose la question : What is the sum of the measures of the angles of a decagon? Penny Nom lui répond. 





A 306090 triangle 
20050911 

Gary pose la question : I have the length of only 1 side of triangle with angles of 306090 degrees. How can I find the length of the other 2 sides? Penny Nom lui répond. 





Is 360 Really the correct value? 
20050815 

Jack pose la question : Considering the circumference of a "Perfect Circle" with a Diameter of 1 meter would be something like 3.14 meters, why do we use the number 360 to represent the number of degrees within that circumference?
Would it not make more sense to express the degrees in reference to the relationship to the diameter as related to pi?
That is, let's just say our "Perfect Circle" has a circumference of 3.14 meters, therefore, what we now consider as due east would change from 90 Degrees to 78.5 Degrees. Penny Nom lui répond. 





The centroid of a triangle 
20050407 

Maria pose la question : Q3)find the coordinates of the centroid of triangle ABC
i want your help here to solve the 3rd question i got stuck. Penny Nom lui répond. 





Each interior angle of a particular polygon is an obtuse angle... 
20050222 

Victoria pose la question : Each interior angle of a particular polygon is an obtuse angle which is a whole number of degrees. What is the greatest number of sides the polygon could have? Walter Whiteley lui répond. 





A 6 sided (hexagonal) pyramid 
20050122 

Steve pose la question : im trying to make a 6 sided (hexagon) pyramid, from 6 triangles of 12mm plywood, i know all the angles to cut apart from the one one to join all 6 triangles together. Rough measurements are outer edge (A) of each triangle is 13cm's, length of other 2 sides (B&C) of triangle outside to center is 14cm's with a height of the whole thing together about 6cm's. Chris Fisher and Harley Weston lui répond. 





Is a square a rectangle? 
20041121 

Carol pose la question : I am a teacher. In an FCAT sixth grade review test, there was a question to the students to draw a square and then they referred to it as a rectangle.
What is the definition that makes a rectangle a square that can be taught to the students without confusing them. Walter Whiteley lui répond. 





Interior and exterior angles of a polygon 
20041116 

Aaron pose la question : How do you find the measure of interior and exterior angles of a regular polygon when you are given the number of sides? Walter Whiteley lui répond. 





Solving triangles 
20041030 

Allen pose la question : Solve the following triangles.
Given
1. B = 20 Degrees, a = 25, b = 16
2. A = 35 Degrees, b = 2, c = 3
3. A = 32 Degrees, C = 44, c = 20 Harley Weston lui répond. 





Two gears 
20041014 

Lindsay pose la question : "There are two gears, a small one on the left and a larger one on the right. The gear on the right makes 1 revolution. The gear on the left makes two revolutions. Suppose the gear on the right is turned through an obtuse angle. Will the gear on the left make a full turn?" Penny Nom lui répond. 





Supplementary angles 
20040923 

Rosemary pose la question : Is the term supplementary angles only applicable to 2 angles (ie. a pair of angles) or can it be used when talking about 3 or more angles that add to make 180 degrees? Penny Nom lui répond. 





Fabricating with pipe 
20040919 

Gil pose la question : I need to fabricate a 10 section, 4" pipe circle with an inside diameter of 40". I would like to know what angles would apply and how to find them, Penny Nom lui répond. 





Water in a cone 
20040728 

A student pose la question : A vertically inverted cone( i.e. vertex down) has a radius 7
inches and height 24 inches. Water is filled to one third of its
height .Find the ht of water when cone is turned upside down Penny Nom lui répond. 





A Fibonacci triangle 
20040425 

Marcelle pose la question : Is it possible to construct a triangle with sides that are three consecutive Fibonacci numbers? Walter Whiteley lui répond. 





The sum of angles in a triangle 
20040406 

A student pose la question : How can u prove sum of angles in a triangle equal to 180 degrees? Penny Nom lui répond. 





Sum of the angles in a pentagon 
20040311 

Ashish pose la question : What is the sum of all the measures of the angles of a Pentagon Penny Nom lui répond. 





A geometry problem 
20040304 

Jennifer pose la question : I need help with this problem: Square ABCD has side length 2. A semicircle with diameter AB is constructed inside the square, and the tangent to the semicircle from C intersects side AD at E. What is the exact length of CE?o Chris Fisher lui répond. 





Napoleon's theorem 
20040227 

David pose la question : How do i prove this : For any triangle, if you make 3 equillateral triangles
using the sides of the the original triangle, the central points of the 3
tringles another triangle that is equillateral.z Chris Fisher and Penny Nom lui répond. 





Sin(3x), cos(3x) and tan(3x) 
20040128 

Jon pose la question : What is the identity for cos3x, sin3x, and tan3x? In class, we learned double angel identities and were asked to find out the identity to these three trig functions. If you can help, please do. Also, i know that the cos^{4}x sin^{4}x is the same as cos2x. Is cos^{8}xsin^{8}x = cos2x also true? Thank you.s Chris Fisher lui répond. 





Reflex angles 
20040109 

Sonya pose la question : My daughter is searching for examples of reflex angles. We already have the hands of a clock but still need another example. Can you help us. Chris Fisher lui répond. 





The angles in a regular polygon 
20031221 

Ernie pose la question : If i have a measure of one interior angle of a polygon, how can i find the number of sides it has? Penny Nom lui répond. 





Finding angles 
20031202 

Jason pose la question : I AM TRYING TO SOLVE A TRIG PROBLEM AND HAVE
FORGOT HOW TO DO IT. WHAT I HAVE IS A RIGHT TRIANGLE WITH SIDE A BEING 14
FEET AND SIDE B BEING 3 FEET, USING PYTHAGOREAMS THEOREM SIDE C SHOULD
EQUAL 14.318 FEET ON A RIGHT TRIANGLE BUT I AM TRYING TO REMEMBER HOW TO
FIND MY ANGLES OTHER THAN THE ONE THAT IS 90 DEGREES. Penny Nom lui répond. 





The area of a triangle 
20031201 

A student pose la question : Find the Area of Triangle ABC
A(3,2)
B(4,0)
C(0,8) Penny Nom lui répond. 





An octagon shaped bed frame 
20031123 

Trish pose la question : My son and I are making an octagon shaped bed frame. We are going nuts trying to figure out what angle to cut the boards to make an outline of an octagon. It seems that the 8 inside angles of the 8 "corners" are 120*, but what is the angle that the 2x6 wood should be cut so that they will angle together to form the outline of the octagon? Penny Nom lui répond. 





Squares in a rectangle 
20031021 

Raj pose la question :
Draw a rectangle with sides of 3 and 4. Divide the sides into 3 and 4 equal parts respectively. Draw squares joining the points on the sides of the rectangle. You will have 12 small squares inside the 3 x 4 rectangle. If you draw a diagonal of the rectangle, it will intersect 6 of the the 12 smaller squares. Similarly, if you have a 4 x 10 rectangle, the diagonal would intersect 12 of the 40 squares inside the rectangle. Is there an algebric equation that determines the number of squares that will be intersected by the diagonal of a rectangle? Chris Fisher lui répond. 





Two chords 
20031007 

Lori pose la question : Chords AB and CD of circle O intersect at E. If AE=4, AB=5, CE=2, Find ED. Penny Nom lui répond. 





Water in a cone 
20030812 

Adrienne pose la question :
Water is poured into a tank in the shape of an inverted right circular cone.ð The height of the tank is 8 m and its radius at the top is 4 m. a. Draw and label a picture to represent this situation.ð (I know how to do this) b. Identify all variable quantities. (h = 8m, r = 4m) c. Find an equation that relates the variable quantities, and reduce the number of variable quantities to two. I was thinking about the equation V = 1/3 pi r^{2} h, which is the Volume of a cone, but I am stumped as to how I am supposed to "reduce the number of variable quantities to two." Can you point me in the right direction? Penny Nom lui répond. 





Cutting some wood 
20030725 

Betty pose la question : My husband is building a six sided wood circle and would like to know the angle to cut the pieces. Penny Nom lui répond. 





An equilateral triangle 
20030317 

Shirley pose la question : An equilateral triangle is one in which all three sides are of equal length. If two vertices of an equilateral triangle are (0,4) and (0,0), find the third vertex. How many of these triangles are possible? Penny Nom lui répond. 





Can a square be considered a rectangle? 
20030227 

Carla pose la question :
Can a square be considered a rectangle? (since opposite sides are same length and parallel) Would a regular hexagon or octagon be considered a parallelogram since its opposite sides are parallel? or does a parallelogram HAVE to have only 4 sides? Penny Nom lui répond. 





A regular polygon 
20030226 

Melissa pose la question : The measure of each interior angle of a regular polygon is eight times that of an exterior angle of the polygon. How many sides does the polygon have? Penny Nom lui répond. 





The area of an isoceles triangle 
20030207 

A student pose la question : I have to find the area of an isoceles triangle with one angle side of 30 degrees, and length of base 5. Could you please help me solve this problem? Penny Nom lui répond. 





Radians 
20030116 

Erikson pose la question : I am a student in the 10th grade and attending advanced math at my high school. I was assign to do a report about the unit circle and the radian. But there seems to be no information available about the history of the radian; who first found out about them, which civilizations used it if any. Well, hopefully you'll assist me in this troubling question. Thank you for your kind consideration. Penny Nom lui répond. 





A Circle is evenly divided into six equal triangles 
20020916 

Marilynn pose la question : A Circle is evenly divided into six equal triangles leaving an area between the outside of the circle and the one side of the triangle. This area is measured as 3.14. What is the length of the radius, one line on the triangle? Paul Betts lui répond. 





The area of a triangle 
20020907 

Phill pose la question : How do you find the area of a equilateral and other triangles? Penny Nom lui répond. 





Find the angle measures 
20020518 

Amanda pose la question : In triangle ABC; the measure of angle A is 20 degrees more than twice the angle B. The measure of angle C Is five times angle B. Find the angle measures. Penny Nom lui répond. 





The law of cosines and obtuse angles 
20020509 

Bryant pose la question : The question that I am pondering is that I need to derive the law of cosines for a case in which angle C is an obtuse angle. Penny Nom lui répond. 





Two triangles 
20020403 

Scott pose la question : Consider 2 triangles: Triangle PMB and Triangle PLA. Triangle PLA is contained within Triangle PMB. Side LA is parallel to Side MB. Point L is located on Side PM. Point A is located on Side PB. If the ratio PL:LM = 5, then what is PB:PA ?? harley Weston lui répond. 





Two circles inscribed in a rectangle 
20020227 

Amina pose la question : Given a rectangle with dimensions L=6, H=5. Two circles are inscribed such that they touch each other(circles are adjacent to each other) and also their circumferences touch 2 sides of the rectangle. One of the circles has radius=4. Find the radius of the other circle. Penny Nom lui répond. 





Similar triangles 
20010908 

Dave pose la question : I am standing on the bank of a river ( whose banks are parallel here) directly opposite a boathouse, B, on the opposite bank. I walk along the bank of the river past a signpost, S, until I reach a point C distant 60 metres from where I started walking. I then walk away from the bank, at right angles to the bank, until I reach a shady tree at D. Attached to teh tree is a sign stating that this spot is 45 metres from the signpost. C is 36 metres beyond S and B and S are in line from D. (a) How far did I walk away from the bank of the river?? (b) Calculate the width of the river? Penny Nom lui répond. 





Bisecting angles 
20010827 

Monica pose la question : Ray QS is the bisector for angle PQR. Find the measure of angle PQS and PQR if the measure of angle SQR is 52 degrees. Penny Nom lui répond. 





Standard angles 
20010805 

Nagaraj pose la question : Why 0^{o} , 30^{o} , 45^{o} , 60^{o} ,and 90^{o} are taken as standard angles in Trigonometry? Why can't we take some other angles as standard angles? Chris Fisher lui répond. 





Radian measure 
20010726 

Amy pose la question : i have to find out what is meant by the radian measure of an angle and compare it to the measure of an angle in degrees. Harley Weston lui répond. 





Rhombus 
20010716 

William pose la question : Calculate the internal angles of a rhombus given measurments of all four sides only. Walter Whiteley lui répond. 





An inequality involving triangles 
20010612 

Sandra pose la question : The triangle inequality guarantees that the sum of the lengths of two sides of a triangle is greater than the length of the third. As a consequence, if x and y are legs of a right triangle, with x less than or equal to y, and z the hypotenuse, then x + y is greater than z, so x is greater than z  y. Under what circumstances will x is greater than 2(z  y) be true? Chris Fisher and Penny Nom lui répond. 





Geometry problems involving triangles 
20010607 

Sandi pose la question : Find the radius of the largest circle contained in a right triangle whose legs are 8 and 15 and hypotenuse is 17. If the right triangle has legs a and b and hypotenuse c, find an expression for the radius of the circle. Penny Nom lui répond. 





The angles in a triangle 
20010511 

Nikki pose la question : Find the measure, to the nearest degree, of each angle of a triangle with sides of the given lengths. 26, 35, 40 Penny Nom lui répond. 





Triangles and fractions 
20010427 

Constance pose la question : My name is Constance and I am thirteen years old (I am a student). The question that I am queering about I don't understand why you do ONE HALF x the base x the width WHEN YOU WANT TO FIND the area of a triangle? My second question is if you multiply one half and 10 together why does it come out as 5? Penny Nom lui répond. 





Squares on a chess board 
20010411 

Tom pose la question : It was once claimed that there are 204 squares on an ordinary chessboard (8sq. x 8sq.) Can you justify this claim? "PLEASE" include pictures. How many rectangles are there on an ordinary chessboard? (8sq. x 8sq.) "PLEASE" include pictures. Penny Nom lui répond. 





The bond angles of a tetrahedral polygon 
20010314 

Nishi pose la question : how do i prove (a simply as possible) why the bond angles of a tetrahedral polygon are 109.5 degrees? *i already have two explanations that i don't understand. one is about "theory of dot products" and "vectors" and a hooklike symbol w/ a cosine, and the other has an incomprhensible diagram w/ difficult notation PLEASE BE SIMPLE! thanks sooo much Harley Weston lui répond. 





How tall is the tree? 
20010302 

Ronda pose la question : a tree's shadow is 42 ft. long. There is a stop sign that is right next to it and it is 18 ft. tall and it's shadow is 12 ft. long. How tall is the tree? Penny Nom lui répond. 





Angles in a polygon 
20010217 

Joan pose la question : How many sides does a polygon have if its smallest interior angle is 120 degrees and each sucessive angle is 5 degrees greater than the predecessor? Penny Nom lui répond. 





The sum of the angles in a polygon 
20010123 

A student pose la question : What is the sum of the measures (interior angles) in an octagon ... heptagon ... decagon. Penny Nom lui répond. 





A lampost and its shadow 
20001224 

Laura pose la question : A lamppost line EC casts a shadow line AC. A 30 cm ruler line DB has been moved from A so that it's shadow falls just within the shadow of the lamppost.  Suppose the length of the ruler's shadow is 42 cm. What is the slope of the imaginary line AE?
 Suppose the lamppost's shadow is 15 m. long. How tall is the lamppost?
Penny Nom lui répond. 





Is this a right triangle? 
20001208 

Alicia pose la question : How would you setup and answer a problem like these one? Triangle ABC has vertices A(2,2), B(1,2), and C (1,2). Use slopes to determine if the triangle is a right triangle. Penny Nom lui répond. 





Triangles and trigonometry 
20001130 

Mose pose la question : If I have a right triangle, and I know the lengths of all three sides, is there a formula that will allow me to determine the measurements of the 2 non right angles? Harley Weston lui répond. 





What are adjacent angles that equal 360 called? 
20001122 

David pose la question : I know that supplementary angles add to 180 degrees and that commplementary angles add up to be 90 degrees, but what are adjacent angles that equal 360 degrees called? Chris Fisher lui répond. 





Length of a shadow 
20001101 

Jessy pose la question : A man who is six feet tall is walking away from a street light that is fifteen feet tall. How long is the man's shadow when he is ten feet away from the light? Penny Nom lui répond. 





Connecting to a water line 
20001020 

Vanja pose la question : My question is...A house is to be connected to a new water main that runs along the line y=2/3x1. The connection point at the house has coordinates (2,9), where the units represent metres. What lenght of plastic pipe is needed to connect to the water main at the closest point? Penny Nom lui répond. 





Trigonometry 
20000902 

david pose la question : determine the sum of the angles A,B where 0 <= A , B <= 180 (degrees) sinA + sinB = sqr(3/2) , cosA + cosB = sqr(1/2) Chris Fisher lui répond. 





Rectangles and algebra 
20000613 

Kirstin pose la question : A rectangle's length is 4 more than twice its width. The area of the rectangle is 336m squared. What is its length? Paul Betts and Penny Nom lui répond. 





Projecting a line segment onto a plane 
20000608 

Monica pose la question : What is the measure of the angle determined by a 14 inch segment and its projection into a plane if the length,in inches, of the projection into the plane is 7 inches? Penny Nom lui répond. 





A centroid problem 
20000602 

Kerstin pose la question : An isoceles triangle has sides measuring 13 cm, 13 cm, and 10 cm. Find the distance from the centroid to the vertex of a base angle. Harley Weston lui répond. 





Adjacent Angles 
20000521 

Katherine Keys pose la question : Can a straight angle be an adjacent angle to another angle? Chris Fisher lui répond. 





Supplementary angles 
20000509 

Suzanne pose la question : We know that: Supplementary angles are two angles whose sum equals 180 degrees and complementary angles are two angles whose sum equals 90 degrees. Are supplementary and complementary angles necessarily adjacent? or can they be nonadjacent? Chris Fisher lui répond. 





sin(7pi/12) 
20000504 

Kristel pose la question : What is the exact value of sin 7pi/12? Chris Fisher and Paul Betts lui répond. 





Monica's geometry problem 
20000427 

Monica pose la question : Given: ABCD is a square; AX is perpendicular to BY Prove: Angle 1 is congruent to Angle 3 Chris Fisher lui répond. 





The side length ratios of some triangles 
20000404 

Alexis Lockwood pose la question : I am doing a project for my Math 30B class regarding the side length ratios of 454590 degree and 306090 degree triangles. I would really appreciate any assistance in answering the following questions, or even direction to an appropriate web site or resource on the matter. Harley Weston lui répond. 





Why a Right angle? 
20000403 

Joseph Mizerek pose la question : I was wondering why a 90 degree angle is called a Right angle. I mean why isn't called a left angle. Haragauri Gupta lui répond. 





Reflex angles 
20000322 

D. Reed pose la question : What is the name of an angle that exceeds 180 degrees? Penny Nom lui répond. 





Building a pyramid 
20000226 

Francis X. Hines Jr. pose la question : I am presently trying to build a pyramid. I can understand that the base has 90 degree angles on the first plane which is the outline of the square that makes up the floor. As close as I can figure the slope of each wall face is 35 degrees or 35.7 to be exact if I am correct by using 360 as the total of the three interior angles.Now , I run into a compound angle where the corners meet what would be the angle created by the two 35 degree angles that would allow for the 90 degree edge to continue. Because I'm working in three dimensions I also need to be sure that my math would be correct when I substract 35 from 90 to aquire the angle of the narrow edge as to allow for a 90 degree surface to be present ..to allow for another level to be added with only the base line being shortened. I hope you can understand what it is that I'm asking assistance with.I would greatly appericate your help. Chris Fisher lui répond. 





Angles 
20000106 

Rayna pose la question : I am doing a presentation report on angles which has to be fun and entertaining as well as educational. I am having problems locating resources on angles that give me ideas of fun entertaining projects. My lecture is to be about 20 minutes long infront of a class of 11th and 12th graders. Please Help if you can. Claude Tardif and Walter Whiteley lui répond. 





Area of a quadrilateral 
19991119 

Zane Cram pose la question : I need the formula to calculate the area of an irregular sided rectangle. Each side has a different measurement or length. Walter Whiteley lui répond. 





Isosceles triangles 
19991012 

Amber pose la question : In defining the types of triangles, our class was stumped by a question asked by one of the student. Maybe you could help. The definition of an equilateral triangle is a triangle with three congruent sides. The definiton of an isosceles triangle is a triangle with at LEAST two congruent sides. The question is, if an isosceles triangle only requires at Least two of the sides to be congruent, could an equilateral triangle be called an isosceles triangle? Penny Nom, Walter Whiteley and Chris Fisher lui répond. 





Two 12sided polygons 
19990925 

Kelly Boulton pose la question : Two 12sided polygons are similar. A side of the larger polygon is 3 times as long as the corresponding side of the smaller polygon. wHAT IS the ratio of the area of the larger polygon to the area of the smaller polygon. Walter Whiteley lui répond. 





Degrees and triangles 
19990909 

Sandra Mills pose la question : Are there any triangles which are not 180 degrees? I am also in need of information on the history of degree measure for an angle. Walter Whiteley lui répond. 





A ladder problem 
19990422 

Michael Blade pose la question : There is a cube box 3feet x 3feet x 3ft resting against a vertical wall on level ground. Resting against the outside corner of the box is a ladder 10 feet tall, this ladder is of course resting on the ground but also against the outside corner of the box and rests on the wall. The question the ladder is divided into two unequal section bounded by the box to the ground and the box to the wall. what are those dimensions? Penny Nom lui répond. 





Angles in Polygons 
19990121 

Jen pose la question :
 How do u find the interior angles of a pentagon when you are given 4 of the angles and you need to find the fifth?
 If you are given the measure of each exterior angle of a regular polygon, how do you figure out how many sides the polygon has?
 i need all information on polygons and how to find their angles!!!
Jack LeSage lui répond. 





Complementary and Supplementary Angles 
19981021 

Christina Saunders pose la question : I am in 9th grade and my math teacher wanted us to find out why complimentary angles are called complimentary and why supplimentary angles are called supplimentary. I have looked everywhere and asked numerous people, but I have yet to find an answer. My math teacher said it had something to do with trigonometry. Do you have an answer for me? Chris Fisher and Penny Nom lui répond. 





The origin of angles 
19980224 

Marc Poulin pose la question : I'm currently teaching angles to students in grade 10 and I've been asked what's the origin of the terms degrees, radians and gradians. I know that the radians come from the sexagesimal numerical system of the Babylonians but my kids wanted to know dates and persons who would have brought these terms first. Harley Weston lui répond. 





The sum of the angles of a triangle is 180 degrees 
19980219 

Quin Liu pose la question : How do you prove that the sum of the angles of a triangle is 180 degrees? Is there a proof? what is it? Chris Fisher lui répond. 





Trigonometric functions 
19971221 

Calvin Cheng pose la question : My name is Calvin and I have a year 12 question for you to help me with. From a point S, the angle of elevation of the top of a tower due north of it is 20 degrees. From R, due east of the tower, the angle of elevation is 18 degrees. S and R are 100m apart. Find the height of the tower. Harley Weston lui répond. 





Shimin's Geometry Problem 
19971202 

Ong Shimin pose la question : ABCD is a rectangle. X and Y are the midpoints of BC and CD respectively. W is a point on AB such that AW : WB = 2 : 1. Z is a point on AD such that AZ : ZD = 2 : 1. WY intersects XZ at O. If the area of triangle WOZ is 84 centimeters squared, find the area of triangle XOY. Chris Fisher lui répond. 





A geometry problem 
19971120 

Herman pose la question : When produced, two equal chords AB and CD of a circle meet at P in an angle of 24 degrees. If H is the midpoint of AB and K is the midpoint of CD, calculate the size of angle HKD. Penny Nom lui répond. 





Triangles, The Pythagorean Theorem and Pizzas. 
19970223 

Sherryle Mathis pose la question : I am a graduating senior presently teaching geometry as part of my student teaching. I will do my CUP on Right Triangles and Pythagorean theorem. I am looking for a fun activity as part of my unit plan. Walter Whiteley lui répond. 





Sides in a Regular Polygon 
19961206 

Rick Moss pose la question : If you are given the measure of each interior angle (162 degrees) of a regular polygon. How many sides does the polygon have? Penny Nom lui répond. 





Height of a Hotel 
19961107 

Irene pose la question : "Irene" is to determine the # of floors in a hotel 500 feet up the street. Irene is on the 10th floor of an office building and can measure the angle of elevation to the top of the hotel, 57 degrees. Her view of the entire building is obstructed. If the street rises at an angle of 8 degrees from the office building to the hotel and the average distance between floors is 11 feet, how many floors are on the hotel? Penny Nom lui répond. 





Why is a circle divided into 360 degrees? 
19960930 

Kurtis Kredo pose la question : I was recently wondering why a circle has been divided in to 360 degrees. When I asked my physics teacher he could not think of an answer. His guess is that it probably has to do with people long ago using the base 6 number system. I have a small inkling that it has to do with easy conversion or usage with radians or grads. Chris Fisher lui répond. 

