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Difficult integration

  1. Jan 1, 2008 #1
    I'm probably missing something obvious here, but I'm trying to integrate the following expression;


    I've tried doing it by part but with no luck. Is there some specific method I need to follow, or is it one of those I can only get by looking it up?
  2. jcsd
  3. Jan 1, 2008 #2


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    ok this is math, not physics.

    Pesonally, I would use the Euler identity for sin(kx) and then things are straight forward, or use a trig-identity. But by heart I never rememeber so many of them, so I almost always use Euler.

    p.s why not using TeX 100%? :)
  4. Jan 1, 2008 #3

    George Jones

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    Let me add some detail to malawi_glenn's two useful ideas.

    Either write [itex]\mathrm{sin}\left(kx\right)[/itex] in terms of exponentials, or write [itex]\mathrm{sin}^2\left(kx\right)[/itex] in terms of [itex]\mathrm{cos}\left(2kx\right)[/itex].
  5. Jan 1, 2008 #4


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    Or, as a third method, use integration by parts+cyclicity of integral.
  6. Jan 2, 2008 #5


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    [tex]\sin^2 x=[1-\cos(2x)]/2[/tex]
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