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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;

    [tex]\int[/tex]sin[tex]{^2}(kx)dx[/tex]

    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

    malawi_glenn

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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

    arildno

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

    pam

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