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**splintercell990****Member**- Registered: 2006-01-23
- Posts: 1

Prove that triangle ABC is a right angle triangle if and only if the following condition is met:

cos(A/2) * cos(B/2) * cos(C/2) - sin(A/2) * sin(B/2) * sin(C/2) = 1/2

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**krisper****Member**- Registered: 2005-12-20
- Posts: 19

As I have to go to school now I will post the proof tonight.

*Last edited by krisper (2006-01-24 05:30:02)*

Humankind's inherent sense of right and wrong cannot be biologically explained.

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