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#1 Help Me ! » Orthogonal projection » 2008-08-27 01:01:37
- atreyyu
- Replies: 1
Does there exist a polyhedron, whose orthogonal projections on some three planes are a quadrilateral, a hexagon and an octagon?
Please help me with this one, I also need a short justification. Thanks 
#2 Help Me ! » Line passing through a square » 2008-08-25 07:20:51
- atreyyu
- Replies: 2
Straight line
passes through the center of a square , whose area is . Let denote the shortest distances between line and points respectively. How to prove that ?#3 Help Me ! » Rectangular prism » 2008-08-03 20:16:27
- atreyyu
- Replies: 1
A rectangular prism, of which the base is a square, has a diagonal of length d, and the total area of all its faces is b. In terms of b and d, what is the total length of all its edges?
#4 Help Me ! » Points on a plane » 2008-08-02 09:53:35
- atreyyu
- Replies: 1
We have a set of points on a plane, and each point has been coloured either red or blue. How to prove that there exists a right and isosceles triangle, whose vertices are all the same colour?
Help! 
#5 Help Me ! » Solutions of a set + determine integers » 2008-08-01 23:01:54
- atreyyu
- Replies: 3
Hey guys! I have 2 algerbra problems and I have no idea even where to begin 
. So could you please solve these problems and *explain* the solution to me? 
1) Determine the number of solutions of the following set, depending on the parameter a.
2) Determine all positive integers
such that is a prime number, and is divisible by 3.Thanks! 
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