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Double integrals

  • Thread starter squenshl
  • Start date
  • #1
479
4
How do I find
J := [tex]\int\int_U y cos(x + y) dA[/tex]
where U = {(x,y) [tex]\in[/tex] R2 : 0 [tex]\leq[/tex] x [tex]\leq[/tex] 2, 1-x [tex]\leq[/tex] x [tex]\leq[/tex] -2 + 2x}.

I drew the picture & i get 2 triangles but not sure what to do with them. Help please.
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,230
31
in rectangular coordinates, dA=dx dy, so the region U describes will give you the limits for the integral.
 
  • #3
68
0
I think you should only be getting one triangle. Try checking your picture against one generated by a graphing tool.

Cheers,
W. =)
 
  • #4
479
4
Very true. I got a triangle & J = -0.5717341110 using maple.
 

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