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Math Help - Derivatives of Trig.

  1. #1
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    Smile Derivatives of Trig.

    Hi!
    The question is to find the derivative of:
    0.5 sin2x + cosx for 0 < x < 2pi

    My answer is:
    sinx + 0.5 cos 2x, but I am not sure if it's correct.
    Thanks in advance,
    Amine
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  2. #2
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    Quote Originally Posted by Aminekhadir View Post
    Hi!
    The question is to find the derivative of:
    0.5 sin2x + cosx for 0 < x < 2pi

    My answer is:
    sinx + 0.5 cos 2x, but I am not sure if it's correct.
    Thanks in advance,
    Amine
    <br />
\frac{d}{dx} \sin(ax) = a\, \cos(ax)

    The derivative of cos is -sin and you forgot the chain rule on the sin(2x) term

    <br />
\frac{d}{dx}[0.5\sin(2x)+ \cos(x)] = \cos(2x)-\sin(x)
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