. centre de ressources dilemmes et doutes le visage humain de mathématiques Qui sommes-nous Problème de mois activités de promotion babillard
Centrale des maths - centraledesmaths.uregina.ca
Dilemmes & doutes
« D & D »
. .
topic card  



liste de
. .
nouvelle recherche

41 articles trouvés pour ce sujet.
A kinky curve 2016-10-06
tammie pose la question :
Koch’s kinky curve is created by starting with a straight segment and replacing it with four segments, each 1/3 as long as the original segment. So, at the second stage the curve has three bends. At the next stage, each segment is replaced by four segments, and so on. How many bends does the curve have at the third stage?
Penny Nom lui répond.
Can you construct a regular 21-gon? 2016-03-08
Peter pose la question :
hi, i know that if i use a compass to draw a circle, i can use the same setting to mark 6 intervals along the circle circumference, how would i go about marking out 21 equally spaced points around the circumference?

if there an online calculator i can us, or some other interesting trick?



Robert Dawson lui répond.
Constructing a cone 2015-03-12
Levi pose la question :
While the mathematics at the welding shop page was very helpful there is one vital part missing. If I have never built a cone how do I figure out how much bigger the diameter of my circle has to be when laying flat on the floor verses the diameter when it has been pulled into a cone.
Harley Weston lui répond.
Constructing a triangle 2013-08-22
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.
A triangle construction 2013-07-27
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.
Drawing an isosceles triangle 2012-05-10
Nazrul pose la question :
How can I draw an isosceles triangle whose each angle adjacent to the base is twice the vertex angle?
Chris Fisher lui répond.
Gravel, sand, cement and an equilateral triangle 2012-03-21
saheed pose la question :
how many tonnes of gravel and sand,bags of cements will be required to concrete 5feet depth/deep of 4feet equilateral triangle?
Harley Weston lui répond.
Making a truncated cone 2011-02-18
lisa pose la question :
We need to make a cone that has the following dimensions.
14-3/8" diameter on large end
13-3/8" diameter on small end
4" tall

What are the dimensions I need to cut in order to make a cone with one seam?

Stephen La Rocque lui répond.
Forming a square 2009-10-21
christianah pose la question :
Two parallel lines have the equations y=x+4 and y=x-2.Two additional lines are drawn to form a square.What is the side length of the square?Write possible equations for the additional lines.Explain and justify your reasoning.
Penny Nom lui répond.
Making a cone 2009-08-19
angela pose la question :
how can i make a cone with a 6cm of heigth and has 2cm radius in the opening??
Stephen La Rocque lui répond.
Constructing an isosceles triangle 2009-07-27
Sanjay pose la question :
How to construct an isosceles triangle ABC with a base BC = 5.4 centimetre and altitude AD = 4.7 centimetre? Please help.
Janice Cotcher lui répond.
Draw an octagon with an area of 18 square centimeters 2008-12-02
Heidi pose la question :
Draw an octagon with an area of 18 square centimeters
Penny lui répond.
A geometric construction 2008-10-17
M pose la question :
Given any 3 parallel lines on a plane, how to construct an equilateral triangle with each vertex on each line?
Chris Fisher lui répond.
A parallel line to a given line 2008-04-12
john pose la question :
A parallel line to a given line through a given point not on the a given line
Harley Weston lui répond.
Constructing the centre of a circle 2007-11-06
Carolyn pose la question :
I have a line segment AB. I need to divide a segment into 3 parts that are congruent. Please help how to divide it. The answer that I was given previous was not the way the teacher wanted it.

I also need information on how to find the center of a circle given an arc.

Penny Nom lui répond.
Dividing a segment into 3 congruent parts 2007-10-30
Carolyn pose la question :
I am doing construction. I have a line segment drawn. I need to divide a segment into 3 congruent part. How do I do that?
Penny Nom lui répond.
An equilateral triangle with height 2 inches 2007-10-23
Christine pose la question :
I'm doing an project in school about tessellations. But first, I have to construct an equilateral triangle with an altitude of exactly 2 inches. I know how to draw an equilateral triangle...but I don't know what I have to do in order for the triangle to have an altitude of 2 inches.
Penny Nom lui répond.
Vehicle collision 2007-07-31
Tania pose la question :
If a driver falls asleep at the wheel of a newer model car and slams into the rear of a parked classic mustang (2860-3280lb) and the parked car is thrown 100 ft across the street, what would be the minimum speed required by the newer car in order to move the mustang?
Penny Nom lui répond.
Constructing an octagonal deck around a circular pool 2007-04-20
Cliff pose la question :
[I am building an] octagonal desk encompassing 17 foot diameter circle for pool. I have seen other octagonal calculations but none of these tell me how much allowance for a circle to fit within the octagon without losing the circle edge can anyone help thanks cliff
Stephen La Rocque lui répond.
A truncated cone 2006-05-28
Phil pose la question :
Hi, I am an art student and I am trying to make a "truncated cone" (ie: a cone with the top cut off) out of sheet metal. I need to design a template first and am having problems working out the angles. The truncated cone is 250mm high, 550mm wide at the bottom and 290mm wide at the top. Can you help?
Stephen La Rocque lui répond.
A truncated cone 2005-12-03
Sonny pose la question :
I need to create a template for a cone that has a 2" opening at the top, a 4" base and stands 6" tall. Can you tell me how to achieve this?
Penny Nom lui répond.
A slump cone 2005-10-27
Wendy pose la question :
we are trying to make a slump cone (used to measure the slump in concrete). It has dimensions of 8" diameter on the bottom, 4" diameter hole on the top and a height of 12". Please help, it is getting frustrating.
Penny Nom lui répond.
A conical hat 2005-10-22
Manish pose la question :
I need to make a conical hat for my daughter's upcoming fancy dress, the circumference of the base(hollow) is 50 cms,the height of the cone is 30 cms,what should be the dimensions of the paper which will make a cone of the beforementioned dimensions?
Penny Nom lui répond.
Constructing a quadrilateral 2005-10-07
Jayasri pose la question :

Can we construct a unique quadrilateral with the following information:

The lenghts of all the sides of a quadrilateral are known.

The angle between one of the sides and the X-axis is known.

Chris Fisher lui répond.
Constructing figures 2005-09-20
Kim pose la question :
I would like to know how to draw different shapes:
Regular Octagon with sides of length, 1 unit
Equilateral Triangles, with sides of length 1 unit
Regular Hexagons, with sides of length 1 unit
Isoseles Triangles, with hypotenuse of length 1 unit

Penny Nom lui répond.
Framing an arched wall 2005-08-12
Mike pose la question :
I'm framing a building wall with a curved (arcing) top section. The radius of the section is 74'6" with a height above finish floor of 16'0". The horizontal run of the arced section is 23' 1 1/2" with a low height above finish floor of 12'4". If I start with a 16' stud at the high end how long are the subsequent studs if they are on 16" centers? Short of laying this out on a tennis court how can I work out the lengths of the studs?
Penny Nom lui répond.
Two matrix problems 2005-03-30
Sue pose la question :
Question 1
Suppose all matrices in the equation below are square and invertible. Solve for x .

BA-1XB-1 + 2BA + In = 0 (the symbol "0" here denotes the matrix of all 0's in it)

Also, A-1 or B-1 is indicating inverse and "In" = for example, A-1 times A
I hope you understand the above. I have to show all the steps.

Question 2
Suppose we consider the set of all 2x2 matrices along with the operations of matrix addition and multiplication. Do they form a field? Why or why not?
I think the answer is no because under multiplication it is not commutative and not all square matrices are invertible. I not positive so I'd like some help.

Penny Nom lui répond.
A matrix construction problem 2005-03-14
Marcelo pose la question :
I want to know if is it possible to solve this problem:
I have an empty NxM matrix and I know totals (sum) by rows and totals by column.
Is there any algorithm to fill the matrix so that the summary of columns and rows gives the original values I have?

Harley Weston lui répond.
Construction of a cone 2004-11-20
John pose la question :
I am a builder working on a project where I need to make a cone. It's a right circular cone with 15" base radius and slant angle of 30 degrees. I want to cut it out of flat sheet metal then bring the edges together to form the cone. Is this enough information?
Penny Nom lui répond.
Constructing a cone 2004-09-07
Steve pose la question :
I am trying to build crayfish traps; one of the components is a cone shaped entry section.

The cone I want to make would be 12" in diameter at the base and 12" in height, from base to peak.

I need a formula to calculate the dimensions and a method of transferring the shape onto a flat piece of material.
Harley Weston lui répond.

Constructing a triangle 2004-08-08
KV pose la question :
Chris Fisher lui répond.
Making a cone 2003-12-22
Tracie pose la question :

I am working on a craft project at home and I have been given the following information:
16" tall and 13" diameter at base, with 1 and 1/2 " opening at top.

Is there a basic formula for creating a cone with this info?

Claude Tardif and Penny Nom lui répond.
A ruler and compass construction 2003-06-29
Mandy pose la question :
I have been searching for instructions on how to do this using a compass. Can you please send instructions step by step on how to bisect a segment into any given number of segments. (example, a way that it will work for bisecting segment into 3, 4, or even 5 congruent parts)
Penny Nom lui répond.
Constructions of polygons 2003-01-03
Garrett pose la question :
Our teacher just finished the constructions unit, and he mentioned briefly about odd sided figures such as pentagons and septagons, only that they're very hard. My question is, how do you draw, with a compass and a straight edge, a pentagon and septagon?
Chris Fisher lui répond.
Construct a pentagon 2002-12-12
Mary pose la question :
We were wondering what the instructions/formula, step-by-step, is to make a pentagon.
Chris Fisher and Penny Nom lui répond.
Constructing a tangent to two circles 2002-11-28
Tom pose la question :
I have two circles, different sizes a known distance from each other. We know the radii of the circles. How do I construct a line that is tangent to both circles relative to the segment that connects the centers of both circles?
Chris Fisher and Penny Nom lui répond.
An equilateral triangle 2002-06-11
Sarah pose la question :
Hi. My name is Sarah. I'm a secondary student taking a Math 30C course by correspondence. The question has two parts.

The first part is: Draw an equilateral triangle XYZ. Draw the altitude from X to YZ. Choose any point P inside the triangle or on the triangle. Draw perpendiculars from P to the sides of the triangle. The Second part is:

Measure the altitude h and the 3 perpendiculars s, t, and u to the nearest mm. Repeat as many time as is necessary until you can state a generalization concerning h, s, t, and u. If you could help me, it would be greatly appreciated.

Penny Nom lui répond.
Constructing the square root of 3 2002-06-07
Allan pose la question :
I am a Math 7/8 teacher. I was wondering how you would show a student how to find the exact location of the square root of three on the number line using just a compass and a straight edge.
Penny Nom lui répond.
Matrix reconstruction 2001-07-19
Guy pose la question :
Is there a way to get the sums of rows, columns and diagonals of an n x n matrix to reconstruct the original matrix?
Walter Whiteley and Patrick Maidorn lui répond.
Constructing an equilateral triangle 2001-04-14
Peggy pose la question :
Please send directions to make an equilateral triangle in plane geometry. I want each student to draw two, cut them out, and place them together to form a Jewish Star.
Penny Nom lui répond.
Two sides and a bisectrix. 1998-11-11
Victor Grinshtein pose la question :
I am looking for someone who can tell me how to construct a triangle by 2 sides and a bisectrix using a compass and a ruler.
Chris Fisher lui répond.



Centrale des maths reçoit une aide financière de l’Université de Regina et de The Pacific Institute for the Mathematical Sciences.



accueil centre de ressources accueil Société mathématique du Canada l'Université de Regina PIMS