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Math Help - [SOLVED] Derivate of cos(arctan x)

  1. #1
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    [SOLVED] Derivate of cos(arctan x)

    How do you do this: d/dx[cos(arctan x)]
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  2. #2
    Math Engineering Student
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    How would you differentiate \cos\big(f(x)\big) ?
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  3. #3
    Master Of Puppets
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    Quote Originally Posted by Amberosia32 View Post
    How do you do this: d/dx[cos(arctan x)]
    Have a look at dot point 5 in Krizalid's sig.
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  4. #4
    MHF Contributor Calculus26's Avatar
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    cos(arctan(x)) = 1/sqrt(1+x^2) = (1+x^2)^(-1/2)

    to see this draw a right triangle with an acute angle u whose opposite side is x and whose adjacent side is 1 making the
    hypteneuse sqrt(1+x^2)
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  5. #5
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    Thank you so much.
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