# Proving expression with sines.

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• February 26th 2011, 10:16 AM
arm
Proving expression with sines.
Prove: $sin^{2}(\alpha -\beta ) = sin^{2}\alpha - sin^{2}\beta +2sin\alpha .sin\beta .cos(\alpha- \beta )$
• February 26th 2011, 01:00 PM
mr fantastic
Quote:

Originally Posted by arm
Prove: $sin^{2}(\alpha -\beta ) = sin^{2}\alpha - sin^{2}\beta +2sin\alpha .sin\beta .cos(\alpha- \beta )$

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