Saturday, 21 December 2013

calculus - Double integral conversions to Polar



Problem 1




Convert to polar form and solve



202xx20((x1)2+y2)5/2 dy dx



x2+y2=2x,r2=2rcosθ,r=2cosθ



π/202cosθ0(r22(rcosθ)+1)5/2rdrdθ



Problem 2




Convert to polar form and solve



113+2yy20cos(x2+(y1)2) dx dy



x2=3+2yy2>x2+y2=3+2y>r2=3+2rsinθ



Is the first problem the right integration to follow in polar?
Im stuck at number 2 in finding the bounds..


Answer




In the case of problem 1, the natural substitution is x=1+rcosθ and y=rsinθ, thereby gettingπ010r×r5drdθ.
The same idea applies to problem 2: do x=rcosθ and y=1+rsinθ.


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