SOLUTION: I have problem with this question: Find the value of sin4A

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Question 39250: I have problem with this question:
Find the value of sin4A
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
sin 4a = sin 2(2a) =
2 sin 2a cos 2a =
2 * (2 sin a cos a) * (cos^2 a - sin^2 a) =
4 sin a cos^3 a - 4 sin^3 a cos a