# Math Help - Proving expression with sines.

1. ## Proving expression with sines.

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

2. 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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