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Math Help - Cosine/Sine

  1. #1
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    Cosine/Sine

    Hey guys Im new here and I am hoping I can get some help.

    write the following as a product of sine and/or cosine of the angles sin (B+C-a) + sin (C+A-B) + sin (A+B-c)-sin (A+B+C)
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ChrisBosh View Post
    Hey guys Im new here and I am hoping I can get some help.

    write the following as a product of sine and/or cosine of the angles sin (B+C-a) + sin (C+A-B) + sin (A+B-c)-sin (A+B+C)
    just apply the addition formula for sine (and cosine) over and over

    Recall: \sin (\alpha + \beta ) = \sin \alpha \cos \beta + \sin \beta \cos \alpha

    and \cos (\alpha + \beta ) = \cos \alpha \cos \beta - \sin \alpha \sin \beta

    Now, you have three terms in the sum for the angles. just apply the rules two at a time


    example: \sin (A + B + C) = \sin [(A + B) + C] = \sin (A + B) \cos C + \sin C \cos (A + B)

    and then you can apply the formulas i mentioned on \sin (A + B) and \cos (A + B)
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  3. #3
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    Quote Originally Posted by Jhevon View Post
    just apply the addition formula for sine (and cosine) over and over

    Recall: \sin (\alpha + \beta ) = \sin \alpha \cos \beta + \sin \beta \cos \alpha

    and \cos (\alpha + \beta ) = \cos \alpha \cos \beta - \sin \alpha \sin \beta

    Now, you have three terms in the sum for the angles. just apply the rules two at a time


    example: \sin (A + B + C) = \sin [(A + B) + C] = \sin (A + B) \cos C + \sin C \cos (A + B)

    and then you can apply the formulas i mentioned on \sin (A + B) and \cos (A + B)
    thank you so much man. really appreciate it. i remember this now.

    o yes and reps added
    Last edited by mr fantastic; January 5th 2009 at 06:51 PM. Reason: Merge
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