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Math Help - identity proof

  1. #1
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    identity proof

    PROVE:
    sin4x = 2sin2xcos2x
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by chopstixdcb View Post
    PROVE:
    sin4x = 2sin2xcos2x
    Use the fact that 4x=2x+2x and that sin(a+b)=sin(a)cos(b)+cos(a)sin(b).
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  3. #3
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    Or, if you already know that sin(2x)= 2 sin(x)cos(x), just replace x with 2x.
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