







Espaces vectoriels 
20020818 

Bacar pose la question : Comment montrer que trois (ou plus que trois) sous espaces vectoriels sont en somme directe. Claude Tardif lui répond. 





Forty foot and 9 spacers 
20190628 

Christopher pose la question : Ok I've got forty foot and 9 spacers one each end and 7 between what is the distance between the seven in the middle Penny Nom lui répond. 





Two spinners 
20180813 

Atina pose la question : A spinner has four equal sectors and a number is written on each sector; 1, 2, 3 and 4. A twodigit number is formed by spinning two times. The number on the first spinning makes the first digit and the number on the second spinning makes the second digit. For example, 2 on the first spinning and 1 on the second spinning make the number 21.
(a) Give the sample space S for the experiment.
(b) Consider the following events : E = odd number; F = number smaller than 35; G = prime number.
Give the subset of outcomes in S that defines each of the events E, F, and G.
(c) Describe the following events in terms of E, F, and G and find the probabilities for the events.
• getting an even integer less than 35.
• getting an odd number or an prime.
• getting an even number greater than or equal to 35 that is a prime number. • an odd number smaller than 35 that is not a prime number.
(d) Are E and F mutually exclusive events? Give a reason for your answer. Penny Nom lui répond. 





An open ball is an open set? 
20160623 

Aqeel pose la question : Theorem: The open ball is an open set? Harley Weston lui répond. 





Travelling in a spacecraft 
20160325 

julie pose la question : if i was travelling in a spacecraft at the speed of light and i turned on my headlight would i see the beam ? Robert Dawson lui répond. 





The line of intersection of two planes 
20151209 

Rabz pose la question : Determine the vector equation for the intersection between the two given planes
2x+7y equal to 14,x+z equal to 7 Penny Nom lui répond. 





A region described by inequalities in cylindrical coordinates 
20150221 

Rahul pose la question : I am not able to visualize a solid given by inequalities as under (in cylindrical coordinate system)
0=
I know that (can visualize) first 2 inequalities say it is a cylinder of infinite length.
It seems that third inequality poses the restriction to the height as well as it makes us to remove a cone.
But I just can not understand it clearly.
Thanks in advance!
Regards,
Rahul Penny Nom lui répond. 





An equilateral triangle with vertices in 3 parallel planes 
20140531 

prajay pose la question : How to construct an Equilateral Triangle whose vertices lie on three
parallel lines, if the distances of two lines are 'a' and 'b' units
from the middle line.What is the length of the side of the
Equilateral Triangle ? Chris Fisher lui répond. 





If x+y+z=1 then x^2 + y^2 + z^2 = ? 
20140430 

Nitin pose la question : If x+y+z=1
then
x^2 +y^2+z^2 = ? ? Robert Dawson lui répond. 





A curve in 3space 
20130214 

pardeep pose la question : we have to show that the curve r(t)=(cos t)i+(sin t)j+(1cos t)k ,0<=t<=2pie;
is an ellipse by showing it to an intersection of a right circular cylinder and a plane.
i got the eqn. of the cylinder but did not get the eqn of plane. Harley Weston 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. 





The triangle inequality 
20100111 

Nazrul pose la question : If A and B are any two vectors, then how can I prove that magnitude of (A+B)<=magnitude of A+magnitude of B. Please show me the process in details. Thank you. Robert Dawson lui répond. 





Elliptic space 
20090918 

Htet pose la question : What is elliptic space and geometry? Robert Dawson and Chris Fisher lui répond. 





Vector spaces 
20090705 

Nazrul pose la question : How can I prove that m(a+b)=ma+mb where a and b are two vectors.
Thank you. Harley Weston lui répond. 





InfiniteDimensional Spaces 
20090626 

Justin pose la question : Hello again, I was also just wondering (in Hilbert Space and Function Space) are there infinitedimensional spaces larger than each other in terms of cardinality? Thanks a lot for your help again!
All the Best,
Justin Victoria West lui répond. 





The column space of a matrix 
20090212 

John pose la question : Question from John, a student:
A=
1 1 0 0
1 1 0 0
0 0 1 0
0 0 1 1
B=
1 5 6
1 5 6
0 7 2
0 0 9
Is the space spanned by the columns of A the same as the space spanned by the columns of B? Harley Weston lui répond. 





A cardboard spaceship 
20080831 

Lee pose la question : I am building a "cardboard" spaceship for my 4 year old grandson.
The cabin is a dishwasher box with a cool control panel and elipse shaped
windows.
I really need help designing the cone or"nosecone".
The diameter of the base is 26", 24" tall, with a 6" diameter opening
at the top.
Thank you for the help!
Lee Penny Nom lui répond. 





Cubic meters, square feet and office space 
20070925 

Kathryn pose la question : Can someone please help and let me know how do you convert 11 cubic meters into square footage? Steve La Rocque and Harley Weston lui répond. 





Two coplanar lines 
20070821 

Robin pose la question : I am going two show that the two lines are coplanar:
(x5)/4=(y7)/4=(z+3)/5
(x8)/7=y4=(z5)/3
I know I have to find a point that lie on both lines, but dont really get it. Stephen La Rocque and Penny Nom lui répond. 





Choosing a bicycle 
20070328 

Jackie pose la question : A specific brand of bike comes in two frames, for males or females. Each frame comes in a choice of two colors, red and blue, and with a choice of three seats, soft, medium, and hard.
a) Use the counting principle to determine the number of different arrangements of bicycles that are possible.
b) Construct a tree diagram illustrating all the different arrangements of bicycles that are possible. c) List the sample space. Penny Nom lui répond. 





The distance from a point to a line in 3 space 
20061029 

Marie pose la question : find the distance from the point (1, 2, 3) to the line x = y = z2 Penny Nom lui répond. 





If a person who weighs 270 pounds on Earth 
20060510 

Chloe pose la question : If a person who weighs 270 pounds on Earth weighs 45 pounds in space, how much would a person weigh in space who weighs 132 pounds on Earth? Stephen La Rocque and Penny Nom lui répond. 





Vectors in three space 
20041030 

Jo pose la question : I have two questions that I just cannot visulise and dont know how to get started on them..!
1. Ship X is sailing North at 4m/s and Ship Y is sailing due East at 3m/s. A sailor on Ship X climbs a vertical pole at 1/2 m/s. What is the velocity of the sailor on Ship X relative to an observer on Ship Y? State it's magnitude and direction.
Not sure where to start with this one...
2. Show, using vectors, that for any tetrahedron, the segments joining the midpoints of the opposite edges are concurrent.
i know what a tetradedron is, and what I am proving but do I solve simultaneously for a specific case?? Walter Whiteley lui répond. 





A 40% increase in garage space 
20041020 

Dianna pose la question : A bus company recently expanded and no longer has enough room in its garage for all of its buses. Twelve of the buses have to be stored outside. If the company decides to increase their garage space by 40%, this will give them enough room for all of their current buses, plus enough room to store another twelve in the future. How many buses does the company own? Penny Nom lui répond. 





A garden space 
20040616 

Carol pose la question : We have a 17' x 19' garden space. If we want it a foot high raised bed, how many cubic yards of topsoil do we need? Penny Nom lui répond. 





Distance in 3space 
20020816 

David pose la question : The question is: how do I figure out the distance of one object in 3D space to another object in 3D space? I have an object at say x = 5.872, y = 2.876, and z = 7.290; and the other object is at x = 1.129, y = 8.213, and z = 11.127. I have been suggested to use the pythagorean theory on this, but since there are three variables, I don't understand how. Penny Nom lui répond. 





A cone in 3 space 
20020320 

Matthew pose la question : Let C in R^{3} be the cone defined by x^{2} + y^{2}  z^{2} = 0 (A) Let P be the plane described by x + 2z = 1 (i) Find a description of P in terms of two parameters s and t . . . Walter Whiteley lui répond. 





A set of points in space 
20020318 

Victoria pose la question : Describe the given set with a single equation or a pair of equations: The set of points in space that lie 2 units from the point(0,0,1) and at the same time 2 units from the point (0,0,1). Penny Nom lui répond. 





Dual spaces 
20011126 

Hoda pose la question : In the book "Linear Functional Analysis" from Epstein there is a proof (page 116) of the following theorem: The dual space of L^{p} is equal to L^{q}. Later, it is stated as a theorem without proof that for 1 <= p < +infinite, The dual space of l^{p} is equal to l^{q}. Doug Farenick lui répond. 





The "pi" of a circle in hyperbolic space 
20011119 

Alex pose la question : How can you find the "pi" of a circle in hyperbolic space (or is it the same). I would like to know because our environment is hyperbolic and if the "pi" of hyperbolic space is irrational, it would follow that space is non discrete. I would greatly appreciate any help in this question. Walter Whiteley lui répond. 





A line in 3 dimensions 
20011017 

Murray pose la question : I'm working on a complicated proof and i need the equation for a line in 3 dimensions. Claude Tardif lui répond. 





Commas in numbers 
20010906 

Mike pose la question : When did the Ontario Education system drop the use of commas in large numbers and replace with a space? Why? Walter Whiteley lui répond. 





Shape, symmetry, measurement and space 
20010224 

Marilyn pose la question : I have to write in detail about how young children learn about shape, symmetry, measurement and space. It is not activities I need it is how the children learn. How/why their brain takes it all in Walter Whiteley lui répond. 





Why the change from commas between every 3rd digit, to spaces instead? 
20010103 

Clarende Duby pose la question : Why the change from commas between every 3rd digit, to spaces instead? For example: Three million three hundred thirtythree thousand three hundred thirtythree written like: 3 333 333 instead of 3,333,333? Does it have something to do with standardizing mathematical notation worldwide? Harley Weston lui répond. 





Networks of satellites and linear spaces 
20001208 

David pose la question : Let us suppose some companies have collaborated to place several satellites in orbit. Let us call the set of all satellites that a given company helped place in orbit a network. Finally let us assume the following 4 rules.  There are at least two distinct satellites.
 For each pair of satellites there is exactly one network containing them.
 Each network contains at least two distinct satellites.
 For each network, there is a satellite not in it.
What is the least number of satellites. what is the least number of networks? Penny Nom lui répond. 





Parking spaces 
20001107 

Lydia pose la question : A parking lot has 4 aisles. Each aisle is about 40 yards long and has parking places on both sides. If a parking place is 3 yards wide, how many cars can the parking lot hold? Penny Nom lui répond. 





Intersection of planes 
19981122 

Dave Rasmussen pose la question : I am a teacher of secondary mathematics with a question about the uses of Three Dimensional Coordinate Geometry. I have been teaching my students to write equations of planes and lines,  to find the intersection of these and the distance between them. What I am having difficulty finding are good applications of these techniques to "real world" situations. Can anybody help me? Walter Whiteley and Harley Weston lui répond. 

