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Homework Help: Integral of Cos^2(x)

  1. Jul 13, 2009 #1
    Could someone walk me through this one? I know what the answer is, but don't really see how that answer is come by. In the book, it just states the answer, so I guess its something obvious, but the answer still eludes me :(


    2. Relevant equations
    [tex] \int{Cos^2{(ax)}}dx[/tex]
     
  2. jcsd
  3. Jul 13, 2009 #2

    Cyosis

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    Homework Helper

    Make sure you know your trig identities.

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