







Tesseract 
20130822 

Dan pose la question : I am not a mathematician. This seems to me an intuitively simple enough problem that I very much need an answer to from someone who's mathematics are better than mine. Please help.
The question is: for a tesseract of side length = 1
what is the distance of the center of each cube from the center of the tesseract ?
I think I have calculated the distance of each vertex from the center, and of the center of each edge from the center, but the question above baffles me.
(anyone not having a clue what I am talking about can brush up here http://en.wikipedia.org/wiki/Tesseract )
Thanks in advance  Dan V Robert Dawson lui répond. 





A polyhedron 
20090310 

Mollie pose la question : Hi, my name is Mollie and I'm in 5th grade. Here's the math problem I have for homework tonight:
"Larissa made a model of a polyhedron using 8 pieces of clay for the vertices and 18 straws for the edges. What type of
polyhedron did Larissa make?"
Thanks. Penny Nom lui répond. 





A 3dimensional star 
20060315 

Rachel pose la question : I am trying to figure out the name of a figure that consists of 8 (I think) square pyramids. There is a net drawing of this figure somewhere and I can't find it because I don't know the name. When all 8 pyramids are connected, they form a '3dimensional star'. We did this project when I was 14 years old and I am now a 27 year old teacher and I would love to do this project with my kids.
chris Fisher lui répond. 





A 3dimensional pie shape 
20050917 

Bill pose la question : Your site appeared in my search for the name of a 3dimensional pie shape. 2d would be a sector of a circle. As it it curved, I don't believe it is in a the polyhedra family. Can you help me find the mathematical term for it? Chris Fisher lui répond. 





A 3 dimensional 5 pointed star 
20011108 

Kent pose la question : I am looking for a formula that will give me a layout for a 3 dimensional 5 pointed star. I want to form it out of sheet metal, using 5 polygons and soldering them at the apex. Can you please help me with this? I would like to be able to give the formula the height of the star from the bottom two points to the top point and also how deep the star is. Thank you very much! Judi McDonald lui répond. 





A four dimensional object 
20010214 

A student pose la question : Can you give me some examples of a four dimensional object you can find around your house? Harley Weston lui répond. 





Find the 3D angle 
20001118 

Jacky pose la question : Included is the diagram. I am trying to find out the angle of ABC. Is it possible? How? Penny Nom lui répond. 





Crown molding mitre cuts 
20001106 

Jim Tomfohrde pose la question : My question has to do with making mitre cuts when installing crown molding. Crown molding is the trim that is put up at the top of walls with one edge on the wall and the other edge on the ceiling. To make a mitre cut on your mitre saw for a 90degree corner you can lay the molding flat on the saw base, set the bevel of the blade to 34 degrees and the mitre to 31.5 degrees (these may be slightly appoximate). Of course depending on which piece of molding you're cutting you will cut one end or the other, or use the left or right end. These angles allow the cuts to line up and form a seamless corner when they're put in place on the wall/ceiling at 90 degrees. My question is this  is there some mathematical formula from which the 34 degrees and 31.5 degrees are derived. I want to know this because in many cases the corner is not 90 degrees but can be more or less, and in these instances I would like to know if I can calculate the bevel and mitre to use based on the angle of the corner. Harley Weston lui répond. 





Three dimensional rectangle 
20000111 

Dennis Murphy pose la question : I would like to find out the name of a Three dimensional rectangle. Harley Weston lui répond. 





Dotted graph paper 
19990408 

Bridget Winward pose la question : A teacher at our school is trying to locate dotted graph paper online or in print. His class would like to make three dimensional, geometerical drawings. Please let us know if you have a good source. Jack LeSage 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. 

