- #1
Noiro
- 24
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Homework Statement
There are 3 parallel lines that are crossed by other 4 parallel lines. So the problem is:
Write a formula by witch you can obtain the number of all parallelograms, if m parallel lines cross n other parallel lines.
Homework Equations
The Attempt at a Solution
I have no idea how to find that formula... I also posted a picture so you'll know how these lines look like.
Thank you.
http://img401.imageshack.us/img401/6647/35670712.png
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