Topic: 3-d list of topics
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10 items are filed under this topic.

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	(3d) Whether line segment intersects triangle		2019-04-13
		From rj: Well hello, Lets say I have a triangle, Not any ordinary triangle, but a triangle that is represented in 3 dimensions. I also have a line segment. Lets say that this triangle has points A(0,0,0), B(1,0,0), C(0,1,1) And the line segment has points D(0,1/2,0), E(1,1/2,1) In what way can I find if the line segment and triangle intersect? Their intersection point? I don't prefer matrices, because they don't make any sense, but ... if that's the only way to solve this, then do what's necessary. Thank you in advance. Answered by Penny Nom.
	3-digit, daily numbers		2011-09-29
		From Margaret: I need the list/group for a raffle that would contain the combinations for a 3 digit (000-999) daily number. There would be 100 tickets sold with 10 3-digit numbers from each numerical group beginning from 000's, 100's 200's, 300's,...900's. No duplicates/replacement. What would be the list of possible combinations of each group of 100 tickets, keeping each different group/list of combinations in separate blocks of 100 tickets without duplication. So I could use 1 list of 100 this year and the next list of combos next year and so forth. Please help! Example: 000,197,245,367,445,569,618,777,842,964 What would be the possible lists of each 100 tickets? Thank you Answered by Penny Nom.
	The volume of 3-D figures		2009-04-29
		From Serena: What is the formula for finding the volume of 3-D figures Answered by Robert Dawson.
	A 3 digit number		2008-01-23
		From Adrian: Consider a 3-digit number,abc,where a is not equal to c.Switch it so that it becomes cba.Subtract the lesser from the greater to obtain rst.Switch this so that it is tsr.Prove that rst+tsr=1089 Answered by Stephen La Rocque.
	Drilling holes in a cube		2006-12-12
		From Liz: What is the volume of the solid remaining if a unit cube has a hole drilled thru one face to the opposite side and the hole that is drilled is a cylinder of unit diameter. Then the cube is rotated and an identical hole is drilled from an untouched face to the opposite side. Then the cube is rotated and an identical hole is drilled between the last two untouched faces. This will result in the cube vertices and the remaining volume of the cube falling into 8 parts. What is the total volume of these 8 parts. How is this volume calculated? Answered by Penny Nom.
	Write the digits 1 to 9 on index cards, ...		2006-10-19
		From Kim: Write the digits 1 to 9 on index cards, arrange the cards to form three 3-digit numbers (using each card only ONCE). The third number is the sum of the first two numbers ** how many different ways can you do this?? ** Answered by Penny Nom.
	A 3-dimensional star		2006-03-15
		From Rachel: 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 '3-dimensional 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. Answered by chris Fisher.
	A 3-dimensional pie shape		2005-09-17
		From Bill: Your site appeared in my search for the name of a 3-dimensional pie shape. 2-d 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? Answered by Chris Fisher.
	A line in 3 dimensions		2001-10-17
		From Murray: I'm working on a complicated proof and i need the equation for a line in 3 dimensions. Answered by Claude Tardif.
	Is a sheet of paper 2-dimensional?		2000-03-06
		From Jaclyn Evans: One day, we were discussing 3-dimensional items. Is a sheet of paper considered a 3-dimensional shape? Or is it 2-dimensional as described by 8.5 by 11 size? Also, could you give me an example of a 4-dimensional item or scenario? Answered by Harley Weston.

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