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Math Help - derivaties of Trigonometric Functions

  1. #1
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    derivaties of Trigonometric Functions

    Here is another one I am stuck on.
    5sinx/(1+cosx)
    this is what I did:

    (1+cosx)d/dx[5sinx]-(5sinx)d/dx[1+cosx]/(1+cosx)^2


    ([1+cos(x)]*(-5)*cos(x)-[5+sin(x)]*[-sin(x)])/([1+cos(x)]^2)

    Where did I go wrong here?

    Thank you!
    Keith
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  2. #2
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    Krizalid's Avatar
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    Quote Originally Posted by keith View Post
    5sinx/(1+cosx)
    f(x)=\frac{5\sin x}{1+\cos x}=5\sin x\cdot(1+\cos x)^{-1}

    Use the product rule.
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  3. #3
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    Quote Originally Posted by Krizalid View Post
    f(x)=\frac{5\sin x}{1+\cos x}=5\sin x\cdot(1+\cos x)^{-1}

    Use the product rule.
    I looked over the problem and noticed it should have been:
    (1+cosx)(5cosx) not -(5cosx)
    Thanx anyway
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  4. #4
    Math Engineering Student
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    Quote Originally Posted by keith View Post
    (1+cosx)(5cosx)
    If you wanna derive this, then just expand 5\cos x+5\cos^2x

    Then apply simple rules of derivation.
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