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Math Help - One angle of triangle

  1. #1
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    One angle of triangle

    I'm not sure what formula is needed to answer the attached question. Maybe the half angle formulae?
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  2. #2
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    Hello Stuck Man
    Quote Originally Posted by Stuck Man View Post
    I'm not sure what formula is needed to answer the attached question. Maybe the half angle formulae?
    \sin A = \sin(\pi-A)
    =\sin(B+C)

    =\sin B\cos C + \cos B \sin C
    Can you see it OK from here?

    Grandad
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  3. #3
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    Grandad had answered the question by the time I written my reply. So I removed it.
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  4. #4
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    Dontcha just hate when he does that!
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  5. #5
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    I found the solution by solving sin C and cos C. Thanks.
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