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Math Help - trig values

  1. #1
    Super Member Random Variable's Avatar
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    trig values

    It's easy to see that is n is an odd positive integer,  \sin\Big(\frac{n \pi}{4}\Big) = \sin\Big(\frac{3n \pi}{4}\Big)

    and if n is an even positive integer,   \sin\Big(\frac{n \pi}{4}\Big) = -\sin\Big(\frac{3n \pi}{4}\Big)

    But how would you prove that?
    Last edited by Random Variable; February 23rd 2010 at 10:12 PM.
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  2. #2
    Moo
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    By induction ?

    Or else, use what you know about odd numbers : if n is even, n=(n-1)+1, where (n-1) is odd.
    and use the addition formula for the sine function.
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