







probleme sin cos 
20060219 

Thibault pose la question : mon probleme commence par: f(x)=sinx (sinx+1)+ cos²x
donc en le dévellopant on trouve: f(x)= sin²x + sinx + cos²x
et apres ce que je ne comprend pas est que par la suite on trouve: f(x)= 1+sinx
qu'estce qui fait que l'on trouve ce resultat?? Claude Tardif lui répond. 





0.366 x cos square (02 degree 17 mins 27 seconds) 
20180312 

michael pose la question : what is 0.366 x cos square (02 degree 17 mins 27 seconds)
what is 0.366 x cos square (88 degree 26 mins 45 seconds) Penny Nom lui répond. 





A footballer angle 
20180214 

Kim pose la question : Two goal posts are 8m apart. A footballer is 34m from one post and 38m from the other. Within what angle must he kick the ball if he is to score a goal. Penny Nom lui répond. 





Solve the equation completely cos 2x = 1 
20170608 

Lava pose la question : Solve the equation completely cos 2x = 1 Penny Nom lui répond. 





How far apart are the boats? 
20161213 

Halley pose la question : Two boats leave port at the same time. Boat A travels east at a speed of 12 km/hr. Boat B travels southwest at a speed of 14 km/hr. After two hours, how far apart are the boats? North is 0 degrees. How do I figure this out.
Thanks Penny Nom lui répond. 





Two airplanes 
20150414 

john pose la question : two planes leave an airport at the same time, one going northwest (N35*W)at 400 mph and the other going east at 332 mph. How far apart are the planes after 4 hours to the nearest mile? Penny Nom lui répond. 





Trig functions and the unit circle 
20141002 

Jake pose la question : I was wondering what conclusions can be drawn about the trigonometric functions and how they work about the circle. Can you also please give me an explanation for it? Thank you. Penny Nom lui répond. 





A triangular chicken pen 
20140427 

Cierra pose la question : Margaret has two lengths of fence, 20 meters and 24 meters, for two sides of a triangular chicken pen. The third side will be on the north side of the barn. One fence length makes a 75° angle with the barn. How many different pens can she build if one fence is attached at the corner of the barn? What are all the possible lengths for the barn side of the pen?
Not sure what they are asking here... please show step by step what to do! Thank you so much! Penny Nom lui répond. 





The sides of a triangle 
20140406 

Michael pose la question : I am supposed to sove for the length of side "b" of an irregular triangle. I am given the following:
Side a: 65'
Side b: Find this length
Side c: 50'
Angle A: unknown
Angle B: unknown
Angle C: 52 degrees
I am supposed to use the law of cosines to solve for side "b" and my teacher
says there is no mistake in the "givens" for the problem. I do not see how
this can be done using the law of cosines and i have not figured out how to sove for
angle B to use the law of cosines. Penny Nom lui répond. 





A triangle problem 
20131002 

raneem pose la question : ABC is a triangle in which : BC=20cm. M(<B) =29 and m(<C)=73 . D is the midpoint of BC
Find the length Of AB and AD approximated to 2 decimal places Penny Nom lui répond. 





We can't write sinx and cosx as a finite polynomial. 
20130331 

rimoshika pose la question : prove that we can't write sinx and cosx as a finite polynomial. Walter Whiteley lui répond. 





The fourth side of an irregular polygon 
20130201 

Emran pose la question : I have a irregular polygon. I know 3 of the 4 sides, and 2 of the angles. AB is 285, BC is 149, and CD is 310. Angle B is 135 degrees. and Angle C is 45 degrees. Is there a formula to solve for the final side? Thanks. Penny Nom lui répond. 





cos(theta/30) = 1 
20120514 

Hope pose la question : cos (theta / 30 = 1
I am very confused as to how to solve it. Can you help? Penny Nom lui répond. 





Tangent of theta 
20120117 

stahl pose la question : explain what the 'tangent of theta' means. Draw and label a diagram to help with your explanation. Harley Weston lui répond. 





Three sides of a triangle 
20111224 

saba pose la question : the three sides of a triangular lot have lengths 10,11and 13cm,respectively.
find the measure of its largest angle and the area of the lot? Penny Nom lui répond. 





How far must the pitcher travel to get to the ball? 
20101104 

ken pose la question : A baseball player bunts a ball down the first base line. It rolls 35ft at an angle of 26 degrees with the first base path. The pitchers mound is 60.5 ft from the plate. How far must he travel to get to the ball. Penny Nom lui répond. 





A radio tower 
20100326 

Alex pose la question : The height of a radio tower is 450 feet, and the ground on one side of the tower slopes upward at an angle of 10 degrees. How long should a guy wire be if it is to connect to the top of the tower and be secured at a point on the sloped side 110 feet from the base of the tower? Harley Weston lui répond. 





A quadrilateral with 4 known sides and 1 known angle 
20100319 

samuel pose la question : Name: Samuel
Status: Student
I have a quadrilateral with 4 known sides and 1 known angle, and I'm trying to evaluate the other angles of my quadrilateral.
By the law of cosines, I can easily find my opposite angle (using the diagonal as a basis for the equation).
However, to find the two remaining angles, I have found no other way so far than to use the other diagonal, which can be found with the equation attached (from geometry atlas).
Is there any simpler way? Robert Dawson and Harley Weston lui répond. 





Solving a triangle 
20100125 

Paige pose la question : how do i solve a triangle with one angle of 73 degrees,
one angle of 32 degrees, and one side of 23cm? Harley Weston lui répond. 





A trig question 
20091215 

A trig question pose la question : Hey, my name is Candle
I'm in academic math10 and am stuck on my trig... one question I thought I had right because i used the cosine law I got wrong and can't figure out why... here's a copy of the question. (i guessed it was D... but my teacher said it's B)
Thanks
Candle Robert Dawson lui répond. 





How fast is the distance between the two cars decreasing? 
20091208 

Jenny pose la question : Two cares are on a collision course toward point P. The paths of the two cars make a 30 degree angle with each other. The first car is 40 km from P, and traveling toward P at 16 km/hour. The second car is 50 km from P, traveling at 20 km/hour. How fast is the (straight line) distance between the two cars decreasing. (Hint: Law of Cosines) Harley Weston lui répond. 





Vectors and the Law of Cosine 
20090608 

lauren pose la question : once force of 20 pounds and one force of 15 pounds act on a body at the same point so that the resultant force is 19 pounds. Find, to the nearest degree, the angle between the two original forces Janice Cotcher lui répond. 





Related rates 
20090309 

Megan pose la question : A plane flying with a constant speed of 330 km/h passes over a ground radar station at an altitude of 3 km and climbs at an angle of 30°. At what rate is the distance from the plane to the radar station increasing a minute later? Harley Weston lui répond. 





Find the resultant of this displacement pair 
20090222 

katydidit pose la question : Find the resultant of this displacement pair:
500 miles at 75 degrees east of north and
1500 miles at 20 degrees west of south.
How do I graph this and how do I solve this problem? Penny Nom lui répond. 





The angle between two lines 
20081217 

abhi pose la question : how to calculate the angle between two lines, given the length of the lines..
angle should vary from 0  360 in the counterclockwise direction Robert Dawson and Harley Weston lui répond. 





The path of a small sailboat 
20081119 

jane pose la question : a sailor in a small sailboat encounters shifting winds. she sails 2.00 km East
then 3.40 km North East, then an additional distance in an unknown direction. Her final position
is 6.68 km directly east of the starting point. find the magnitude & direction
of the third leg of the voyage. Harley Weston lui répond. 





How far are the boats apart? 
20081114 

dom pose la question : Two boats leave port at the same time. They leave at 150 degree angle. One boat travels at 10mph and the other at 20mph. After two hours how far are the boats apart? 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. 





Radii and Chords Create a NonRight Triangle 
20080822 

Beary pose la question : AOC is a diameter of circle O. Line AB is 12, and lines OA and OC (the radii) are 10. Find the length of line BO and chord BC. Janice Cotcher lui répond. 





Arclength and sectorangle 
20080806 

Benson pose la question : If chord length, radius are given, How to find the sector angle and arclength Janice Cotcher lui répond. 





Guy wires for a tower 
20080519 

larissa pose la question : a radio tower 500 feet high is located on the side of a hill ( the hill has an inclination to the horizontal of 5 degrees.) How long should two guy wires be if they are connected to the top of the tower and are secured at two points 100 feet directly above ( up the hill ) and directly below the base of the tower? Penny Nom lui répond. 





The length of the third side of a triangle 
20080216 

mary pose la question : I have an angle of 72 degrees and each of the sides are 5' long. What is the distance from each of the ends of the 5 feet to form a triangle. Stephen La Rocque lui répond. 





The cosine of an angle 
20080121 

Kristine pose la question : Find measure of unknown side
cosA=0.5 Harley Weston 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. 





How far is the jet from the lighthouse? 
20080107 

Natalie pose la question : Question: A ship spots a lighthouse that is 53m high, at an angle of elevation of 7 degrees that is directly north of the ship. The same ship spots a jet travelling N62E at an altitude of 1500m with an angle of elevation of 15 degrees. How far is the jet from the lighthouse?
Natalie Harley Weston lui répond. 





The definition of the sine function 
20071122 

Indrajit pose la question : I need a explanation in this theory.......if sinθ = p/h...then
sin 90 deg. = p/h
or 1 = p/h
or p=h .....how can a perpendicular be equal to a hypotenuse.??? Harley Weston lui répond. 





Area of a quadrilateral 
20071010 

Courtney pose la question : how would i find the area of a quadrilateral..
the sides are a (/) is 6cm, b (—) is 9 cm, and c (\) is 7 cm..
the angle between a and b is 140 degrees and b and c is 115 degrees.. Stephen La Rocque lui répond. 





The length of the third side of a triangle 
20070815 

Brooklyn pose la question : What is the equation to find the length of the third side of a triangle if you have the length of A, B, and the angles(s)? Stephen La Rocque lui répond. 





Calculating the area (acreage) of a four sided lot 
20070718 

A property owner pose la question : I have a real estate property and the lot size is something I need to find out. I know the lengths of the four sides, but it isn't a rectangle, it is an odd shape. How do I find the acreage? Stephen La Rocque lui répond. 





Trig functions for angles not between 0 and 90 degrees 
20070716 

Tim pose la question : My question: Why is the value of a trigonometric function, the same, for an angle over 90 degrees and its reference angle?
How are the angle and its reference related? Do they both form a triangle that has equal sides? Penny Nom lui répond. 





Any regular polygon inscribed in a circle 
20070712 

DJ pose la question : Circle with r=12" is inscribed in a regular octagon. What is the length of each octagon segment?
Note: Our answer works for any regular polygon inscribed in any circle. Stephen La Rocque lui répond. 





sinx and cosx 
20070625 

Mac pose la question : Can anyone tell me whether sinx and cosx is differentiable at x=0 ?
As far as i know, cos(x) and sin(x) is differentiable at all x. Penny Nom and Stephen La Rocque lui répond. 





The area of a quadrilateral 
20070610 

Lucy pose la question : Calculate the area of the quadrilateral ABCD.
AB= 4.1cm, BC = 7.6cm, AD= 5.4 cm, CD= ?
Angle ABC = 117, Angle ADC = 62.
Give your answer correct to 3 significant figures. Stephen La Rocque and Penny Nom lui répond. 





Evaluating sine and cosine 
20070506 

Selimovic pose la question : How can i solve sine or cosine for angle of, lets say 10°....Maybe
it's easy but i don't know how... Penny Nom lui répond. 





The law of cosines 
20070323 

chetna pose la question : Q 1) In triangle LMN, l=7, m=5 , n=4. find ANGLE N.
After applying the rule and substituting values i'm getting
Cos n= 58/40. Is there something wrong. The answer at the back of the book is 34 degrees. Penny Nom lui répond. 





A curve on a cylinder 
20070127 

John pose la question : think of a tube,say 50mm in diameter made out of cardboard, project vertical lines at right angles from the base at say every 2mm right round the tube in pencil.No pretend you can put this cardboard tube in a saw and cut it at 45degrees. Get a pair of scissors and cut it at the lowest end and lay it out flat.It now looks like a graph,how do you work out each of these vertical lengths possibly chord lengths Stephen La Rocque and Penny Nom lui répond. 





lim x>infinity cos x 
20061207 

Katie pose la question : I was wondering if it was possible to find: lim x>infinity cos x Stephen La Rocque lui répond. 





cos2x=1 
20061121 

Christina pose la question : I'm have a hard time solving cos2x=1 for exact values between 0<_x <360 Stephen La Rocque and Penny Nom lui répond. 





A trig problem 
20060624 

Greg pose la question : A and B are two towers, B being 4 km due east of A. The true bearings of a flagpole, C, from A and B are α east of north and α west of north respectively. The true bearings of a second flagpole, D, from A and B are (α + β) east of north and (α  β) west of north respectively. Assuming A, B, C, and D are on level ground, and that α = 25, β = 10, find the distance between C and D. Penny Nom lui répond. 





The chord length of a polygon 
20060614 

Krishna pose la question : I have to find out the chord length of a polygon  Tetradecagon ! The Radius of the Circle is 11.5 Cms. The Circle is intersepted by 14 arcs. Then how to find out the chord length? Stephen La Rocque lui répond. 





The interior angles of a right triangle 
20060520 

Greg pose la question : I am wondering if there is a way to figure out the interior angles of a right triangle if we know ONLY the side lengths, and the trick is, we CANNOT use arctangent! Leeanne Boehm and Penny Nom 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. 





Three towns are located at the vertices of an equilateral triangle 
20060320 

A student pose la question : three towns are located at the vertices of an equilateral triangle. The towns are 8, 5, and 3 miles, respectively, from a store. How far apart are the towns? Chris Fisher 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. 





The period of sin(x) + cos(x) 
20050721 

A student pose la question : WHAT IS THE PERIOD OF SIN(X)+COS(X)? Penny Nom lui répond. 





The tide at a boat dock 
20050111 

Abraham pose la question : The tide at a boat dock can be modeled by the equation
y = 2cos(pi/6 t) + 8,
where t is the number of hours past noon and y is the height of the tide, in feet. For how many hours between t=0 and t=12 is the tide at least 7 feet? Penny Nom lui répond. 





Modelling monthly temperature with a cosine 
20041225 

Regis pose la question : The average monthly temperature for a location in Ontario as a function of month number can be modelled using the equation y = a cos[k(t + b)] + d. Harley Weston 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. 





Finding bearings 
20040524 

James pose la question : This question is about finding bearings. A boat race starts from point A, goes North to Point B, a distance of 1000 meters. The course is triangular. The bearing from point B to point C is South 70degrees West. The distance from Point B to point C is 1500 meters. Find the course bearing from C to A.
Penny Nom lui répond. 





Cosine of 35 degrees 
20040303 

Jason pose la question : How do you find the exact solution to cosine 35 degrees. Chris Fisher 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. 





Laws of sines and cosines 
20031123 

A parent pose la question : On the one side of a stream lines PA= 586.3 feet, PB = 751.6 feet are measures, angle APB being 167 degrees and 36 min. Q is a point on the opposite side of the stream. Angle PAQ=63 degress and 18 min and PBQ=49 degrees and 24 min. Find PQ. Penny Nom lui répond. 





Odd powers of sine and cosine 
20030625 

Antonio pose la question : Can you please tell me how to integrate a trig function involving sine and cosine? I know if the powers of both the sine and cosine are even and nonnegative, then I can make repeated use of the powerreducing formulas. But for the question I have on my hand, the powers of both sine and cosine are odd: ( sin3x + cos7x ) dx. Harley Weston lui répond. 





Two trig problems 
20030610 

Bett pose la question :
I have this ongoing trouble with trig and solving triangles with laws of cosines and sines!! For example if it asks to solve triangle FGH, given angle G=102.7 , side f=14.2, and h=18.6. Now do I use law of cosines because I don't have the measure of an angle and length of the opposite side??I don't know where to go from here,I am totally confused!!! I also have a problem with this word problem I have been doing. It asks: An airplane flies 847.5 km at a bearing of 237.3 degrees. How far south and west fo its original position is it? Huh? Please help! Penny Nom lui répond. 





sin theta = 7/8 
20030507 

Patty pose la question : If sin0 = 7/8 and 0 is in quadrant 2, find the other five trigonometric functions of 0. (report your answers in radical form) Penny Nom lui répond. 





Write sin(3x) in terms of sin(x) 
20030505 

A student pose la question : Write sin 2x in terms of sin x Penny Nom lui répond. 





How far apart are the transmitters? 
20020518 

Jeff pose la question : A ship at sea is 70 miles from one transmitter and 130 miles from another. The measurement of the angle between the signals is 130 degrees. How far apart are the transmitters? 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. 





A trigonometric identity 
20020322 

Debby pose la question : I am stuck on a problem and wondering if you can help?? It is: Prove the following: sec^{2}(X)+csc^{2}(X) = sec^{2}(X)csc^{2}(X) Harley Weston lui répond. 





sin 2x = cos 3x 
20020225 

Allan pose la question : solve: sin 2x = cos 3x Primary question: how do you handle the cos 3x? Paul Betts and Chris Fisher lui répond. 





Adding vectors 
20020112 

Lena pose la question : how do you add vectors together? If you are given the length and angles of both vectors and are asked to add/subtract them, how do you do it? I know you are supposed to do the head to tail method, but whenever i try it i get the wrong answer. I need help setting it up. example: A is 2.7cm, and 60 degrees, B is 1.6cm and 135 degrees, find the magnitude and amplitude Penny Nom lui répond. 





The tangent function 
20020112 

Justine pose la question : if you know that sin45degress = cos45degrees, how do you know that tan45degrees = 1? Penny Nom lui répond. 





A trig identity 
20010727 

Jeff pose la question : prove this identity and show steps tan(x/2+pi/4)=secx+tanx Harley Weston lui répond. 





The speed of the boat 
20010712 

Sharon pose la question : A motor boat is travelling in a southeasterly direction in water that is flowing from the south at 2km per hour. Show that the speed of the boat is (6 times the square root of 2) km per hour, given that it can travel at 10km per hour in still water. 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. 





The unit circle and trigonometry 
20010405 

Ashley pose la question : "My teacher wants us to find out what a unit circle is, which I found out, a circle with the radius of 1, but the problem is he wants us to show the relationship between the unit circle and the sine(30,45,60 degrees), cosine(30,45,60 degrees),and tangent ratios(30,45,60 degrees). I need help with this and my teacher will not help us out. Thanks very much ... Penny Nom lui répond. 





The law of cosines in the real world 
20010221 

Hope pose la question : Do you have any examles and/or labs that show how the law of cosines is used in the real world? Harley Weston lui répond. 





Law of cosines 
20010220 

Emily pose la question : I missed a few days of class and I can't figure out how to solve Law of Cosines problems. I have the notes and formulas but I can't figure out how to do the math involved to answer the problems. I am also getting confused about how to use degrees and seconds in the Law of Sine and Cosine. I can't seem to get the correct answers and I don't really know how to solve them and enter them into my TI 86. Harley Weston lui répond. 





The laws of sines and cosines 
20010102 

Faydene pose la question : Can the sine /cosine rule be applied to a right angle triangle to find a particular solution or are these 'rules' applied only when the triangle is not right angled? Penny Nom lui répond. 





Trig identity crisis 
20001129 

Rhiannon pose la question : I have tried many times to find the answer to these problems but I can't I am in grade 12  tan(x)=csc2(x)cot2(x)
 cos(x)/csc(x)2sin(x)=tan(x)/1tan(x)
 cos(x)[ tan^{2}(x)11]/cos^{2}(x)+sin^{2}(x)=sec(x)
Harley Weston lui répond. 





Some trigonometry 
20000811 

Angela pose la question : I have some PreCal questions. I am a student at the secondary level. I would be very grateful for your help. Solve the equation for theta (0 <= theta < 2pi). tan^{2}(theta) = 3 I know sec^{2}(theta) 1 = tan^{2}(theta) . . . Harley Weston lui répond. 





Using the inverse sine function 
20000531 

Nelson Rothermel pose la question : This has me completely baffled. I have to use the laws of sine or cosine to find the angles of a triangle when I have 3 sides, so I can't go 180xy when I have 2 angles. Now, I have a triangle with values of 3, 7, and 9. Here are the steps I used (A,B,C are angles; a,b,c are opposite sides): angle A (16.1951 degrees): cos^{1}*((b^{2}+c^{2}a^{2})/(2*b*c)) angle B (40.6011 degrees): sin^{1}*(b*sin(A)/a) angle C (56.7962 degrees): sin^{1}*(c*sin(A)/a) If you notice, A+B+C does not equal 180. According to the book, A and B are correct, but C is supposed to be 123.2038 degrees. Why doesn't it work??? Harley Weston lui répond. 





Solve 2sin 3x1=0 
20000511 

Cynthia pose la question : How would you solve 2sin 3x1=0? I don't know what to do with the 3. Penny Nom 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. 





Triple angle formula 
20000223 

Sara pose la question : Can one derive a triple angle formula for sine and cosine? If so, how? Chris Fisher lui répond. 





A trig identity 
20000217 

Eric pose la question :
Question: How do I solve this problem? sin3x cos3x _____  _____ = 2 sinx cosx Chris Fisher lui répond. 





Sines & cosine laws 
19991210 

Pierre Boivin pose la question : Triangle LMN, angle L=71 degree , LM= 7.2 , MN=8.3 , ln= 5.9 The questiion was to find angle M. Using the cosine law I found the answer to be 44 degree. It is also the book answer. Using the sines law I found the answer to be 42.2 degree. why can't I use the sines law. Chris Fisher lui répond. 





Cos x = 1/2 
19991201 

Pierre Boivin pose la question : When I factor[ 2cos (square)  5cos 3], I get (2cos + 1)(cos  3). 2cos + 1 = 0, 2cos = 1, cos = 0.5,. Using inv cos on calculator, I get 120 degree related angle. When I graph I get two values, between 90 and 180 degree and between 180 and 270 degrees. How do I find those two values. How do use 120 degree in relation with the x axis. Penny Nom lui répond. 





A Trigonometry Question 
19990828 

Diane Simms pose la question : My question is can the following be factored. I am a teacher who needs the factors to this right away. 2 Sin^{2}X + 2 SinX CosX  1= 0 Harley Weston lui répond. 





From an airport control tower 
19990804 

Pammy pose la question : Hi I am a 30 yo mature age student doing my HSC but am having difficulty understanding this, if you can help me. From an airport control tower, a Cessna bears 023 degrees T and is 27km away. At the same time, a Boeing 767 bears 051 degrees T and is 61km from the tower. Both planes are at the same height. i) What is the size of angle ATB? ii) Using the cosine rule to calculate the distance the planes are apart, to nearest kilometre. I figured out and drew the triangular diagram but can't figure out the rest and which formula to use. sorry about this, thankyou kindly Harley Weston lui répond. 





Sin 4A 
19990622 

Ryan Cochrane pose la question : If sinA = 4/5, and A is a first quadrant angle, find sin4A Harley Weston lui répond. 





Cos(x) Cos(2x) Cos(4x)=1/8 
19970924 

Tan Wang pose la question : How many distinct acute angles x are there for which cosx cos2x cos4x=1/8? Chris Fisher Harley Weston and Haragauri Gupta lui répond. 





Finding the Mine 
19970623 

Billy Law pose la question : Tom is gold prospector. On his last trip out from town, he headed 35 degree South of West to a lake where he had lunch. The lake was 24 km out of Town. He then headed due East for 35 km before Doubling back on bearing of 15 degree South of west for 20 km to reach his mine. By converting to Cartesian coordinate before doing vector additions do the following: a) Calculate the position of the mine from town in term of a distance and a direction. ... Harley Weston lui répond. 





A problem with arccos. 
19970609 

Vanessa Chan pose la question : Prove: arc cos4/5 + arc cos (5/13) = arc cos (56/65) Harley Weston lui répond. 





Ajax, Beverley, Canton and Dilltown 
19970314 

S. Johnson pose la question : The following towns are placed on a coordinate system. Ajax at (x,z), Dilltown at (10,0), Canton at (0,0) and Beverly at (0,10). The roads from Beverly to Canton and from Canton to Dilltown are perpendiculat to each other and are each 10 miles in length. A car traveling at all times at a constant rate, would take 30 minutes to travel straight from Ajax to Canton, 35 minutes to travel from Ajax to Canton via Beverly, and 40 minutes to travel from Ajax to Canton via Dilltown. What is the constant rate of the car, to the nearest tenth of a mile per hour. Chris Fisher and Harley Weston lui répond. 





A trig problem 
19961213 

S. Johnson pose la question : sin t + cos t = 1/5. Find ALL exact values of cot t, given the original equation. Harley Weston 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. 





A trig identity 
19960311 

Azmat Hussain pose la question : Is there an easier/another way to prove the trig identity cos(a+b) = cos(a)cos(b)sin(a)sin(b)? Penny Nom lui répond. 

