1. The problem statement, all variables and given/known data Take the double integration of http://webwork.usi.edu/webwork2_files/tmp/equations/08/1294e87299342c0ccfe2f8a97055da1.png when f(x)=sqrt(4x-x^2) 2. Relevant equations x=rcos(theta) y=rsin(theta) 3. The attempt at a solution I know I plug in the r*cos(theta) and r*sin(theta) for the x and y in the equation I am integrating, but other than that i can't remember how to switch the limits about which I integrate. After I substitute and simplify I get double integral of 1 dr dtheta. How do I change the limits of the integration to polar?