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Homework Help: I forgot how to do the partial derivative of sin(x)cos(x), respect to x. Need Help!

  1. Sep 10, 2008 #1
    1. The problem statement, all variables and given/known data

    partial derivative (d/dx) sin(x)cos(x)

    2. Relevant equations

    Partial Derivatives, product rule

    3. The attempt at a solution

    sin(2x) = 2 sin x cos x, therefore y=sin(2x)/2

    so y'=cos(2x)*(2/2) = cos (2x)?

    Is this correct?
    Is there an easier way of directly finding the derivative without using substitution?
     
  2. jcsd
  3. Sep 10, 2008 #2
    Re: I forgot how to do the partial derivative of sin(x)cos(x), respect to x. Need He

    I don't see why you would be using partial differentiation with this problem? It is not a product of two variables?

    No, that's the quickest method. Use the trig identity to avoid product rule.

    Either way, GOOD JOB!!!
     
    Last edited: Sep 10, 2008
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