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Double integral help

  • #1
1,197
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:

Answers and Replies

  • #2
Galileo
Science Advisor
Homework Helper
1,989
6
Don't forgot the lower limit in the first integration: [itex]\sin(x+\pi/4)-\sin(x)[/itex]
 

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