Double Integral - Polar Coordinates

duki
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Homework Statement



Evaluate by changing to polar coordinates

Homework Equations



Can't figure out how to make the integral stop after the sqrt(9-x^2)
\int_0^\frac{3}{\sqrt(2)} \int_x^{\sqrt(9-x^2)} e^-(x^2+y^2) dy dx

The Attempt at a Solution



I'm not sure where to really start on this one. I know it will end up being e^-r^2 but beyond that I'm not sure.
 
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You'll have to express dxdy in other variables, and the intervals have to be changed.
 
How can I change them to polar coordinates?
 
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First of all: Draw a figure in the xy-plane with to see what shape the domain yields (probably something like a circle sector). Then you should be able to figure out what values you should give r and \phi. You usually substitute r*drd\phi for dxdy when using polar coordinates. However, the exact expression depends on what shape the domain yields.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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