Friday, 20 June 2014

calculus - Changing the order of integration on a rectangular and polar region




change the order of integration for the following integral from dydx to dxdy, and from dydx to polar coordinates.
f(x,y)dydx



where
0y(x2)+2
0x1



From dydx to dxdy
f(x,y)dxdy+f(x,y)dxdy




First integral
0x1
0y1



Second integral
0x(2y)
0y1



I'm not sure about the (2y) for the bounds of x for the second integral.



__




I'm having more trouble converting this into polar coordinates though. I think I can leave the first integral as it is in terms of dxdy, because the region is a rectangle. Is there any way to switch this rectangular region into polar coordinates?



For the second integral



0r1
0θπ/2



f(x,y)dxdy+f(r,θ)rdrdθ


Answer




your work fipping the order of integration is correct.



coverting to polar -- it is going to get messy.



x=rcosθy=rsinθ



Inside the rectangular region.



θ[0,π4)x=1rcosθ=1r=secθ



Inside the parabola



θ[π4,π2]y=x2+2rsinθ=r2cos2θ+2r2cos2θ+rsinθ2=0r=sinθ+sin2θ+8cos2θ2cos2θ



I wouldn't want to integrate that, but it would be a limit.


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