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Math Help - how to replace the sinus..

  1. #1
    MHF Contributor
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    how to replace the sinus..

    http://i45.tinypic.com/r9lfg5.jpg

    i found a_n b_n a_0
    but i need to replace the sines
    like (-1)^n=cos(pi*n)

    i dont know how to do it which sines
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  2. #2
    Banned
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    Quote Originally Posted by transgalactic View Post
    http://i45.tinypic.com/r9lfg5.jpg

    i found a_n b_n a_0
    but i need to replace the sines
    like (-1)^n=cos(pi*n)

    i dont know how to do it which sines

    Are you actually asking what's \sin\left(\frac{\pi}{2}\pm n\pi\right)=\left\{\begin{array}{rc}1&,\mbox{if } n\in 2\mathbb{Z}\\-1&,\mbox{if } n\notin 2\mathbb{Z}\end{array}\right. ?? This is trivial, so perhaps I misunderstood.

    Tonio
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  3. #3
    Super Member Bacterius's Avatar
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    Quote Originally Posted by tonio View Post
    Are you actually asking what's \sin\left(\frac{\pi}{2}\pm n\pi\right)=\left\{\begin{array}{rc}1&,\mbox{if } n\in 2\mathbb{Z}\\-1&,\mbox{if } n\notin 2\mathbb{Z}\end{array}\right. ?? This is trivial, so perhaps I misunderstood.

    Tonio
    Tonio, I have a quick question. What does n \in 2 \mathbb{Z} mean ? Does it mean that n = 2k with k \in \mathbb{Z} ? (Sorry for my ignorance)
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by Bacterius View Post
    Tonio, I have a quick question. What does n \in 2 \mathbb{Z} mean ? Does it mean that n = 2k with k \in \mathbb{Z} ? (Sorry for my ignorance)
    It means that n is an even integer.

    CB
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