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Homework Help: Double integral help

  1. Mar 16, 2006 #1
    [tex]\int _0 ^{\pi/3} \int _0 ^{\pi/4} x cos(x+y) dy dx[/tex]
    [tex]\int _0 ^{\pi/3} xsin(x+\frac{\pi}{4}) dx [/tex]
    using u-sub, u=x, dv=sin(x+pi/4)

    [tex]-xcos\left(x+\frac{\pi}{4}\right)+ sin\left(x+\frac{\pi}{4}\right)-sin\left(\frac{\pi}{4}\left) |_0^{\pi/3} [/tex]

    [tex]-\frac{\pi}{3}cos\left(\frac{\pi}{3}+\frac{\pi}{4}\right)+ sin\left(\frac{\pi}{3}+\frac{\pi}{4}\right)-sin\left(\frac{\pi}{4}\right) [/tex]

    i dont know where I made the mistake
    Last edited: Mar 16, 2006
  2. jcsd
  3. Mar 16, 2006 #2


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    Homework Helper

    Don't forgot the lower limit in the first integration: [itex]\sin(x+\pi/4)-\sin(x)[/itex]
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