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Math Help - dy/dx

  1. #1
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    dy/dx

    i am kind of confused on which rule to use?

    Find dy/dx

    y=cos^2 (3x)+sin^2(3x)


    step by step
    Last edited by Emmeyh15@hotmail.com; January 22nd 2009 at 07:44 AM.
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  2. #2
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    Hello, Emmeyh!

    This is a trick question . . .


    Differentiate: . y \:=\:\cos^2(3x)+\sin^2(3x)
    We know that: . \sin^2\!\theta + \cos^2\!\theta \:=\:1 . . . right?

    So the function is actually: . y \:=\:1

    Therefore: . \frac{dy}{dx} \:=\:0


    And you should get the same answer doing it "the long way."
    .
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