SOLUTION: prove the following as an identity; cos(a-b) - cos(a+b) = 2sin(a)sin(b)

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Question 756827: prove the following as an identity;
cos(a-b) - cos(a+b) = 2sin(a)sin(b)
Answer by Cromlix(4381)   (Show Source): You can put this solution on YOUR website!
cos(a - b) = cosacosb + sinasinb
cos(a + b) = cosacosb - sinasinb
= cosacosb + sinasinb -(cosacosb - sinasinb)
= cosacosb + sinasinb - cosacosb + sinasinb)
= sinasinb + sinasinb
= 2sinasinb Proved
Hope this helps
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