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Math Help - Triangle Prove

  1. #1
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    Smile Triangle Prove

    For any triangle, show that cos(Y/2) = sqrt{[2(2 - c)]/(ab)}
    where s = (a + b + c).

    Hint Given:

    Use the Half-angle Formula and the Law of Cosines.
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  2. #2
    Moo
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    Quote Originally Posted by magentarita View Post
    Use the Half-angle Formula and the Law of Cosines.
    Why do you post if you know what to do ?
    Last edited by Moo; September 14th 2008 at 09:06 AM.
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by magentarita View Post
    For any triangle, show that cos(Y/2) = sqrt{[2(2 - c)]/(ab)}
    where s = (a + b + c).

    Hint Given:

    Use the Half-angle Formula and the Law of Cosines.
    I'll bite. What's Y? And where does the s come into the equation?

    -Dan
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