# Help with an integral

1. Nov 27, 2008

### eoghan

Hi there!
I have to calculate the integral of the function sqrt(x^2+y^2) over the circle (x-1)^2+y^2<=1

I use polar coordinates: rho goes from 0 to 2cos(theta) and theta goes from 0 to 2pi.
My result is that the integral is 0... is it right?

2. Nov 27, 2008

### jeffreydk

Yea I did it and got 0 because you end up integrating $\cos(\theta)^3$ at the end, which is 0.

3. Nov 27, 2008