1. The problem statement, all variables and given/known data Use polar coordinates to find the volume of the solid inside the hemisphere z=sqrt(16-x^2-y^2) and inside the cylinder x^2+y^2-4x=0 2. Relevant equations z=sqrt(16-x2-y2) x2+y2-4x=0 x=rcos(Θ) y=rsin(Θ) z=√(16-r2) 3. The attempt at a solution ∫∫ r√(16-r2) dr dΘ The problem is the bounds; because the circle isn't centered it's throwing me off. Would dr be from 2 to 4? That's the start and end of the radius as it's a circle centered at (2,0) with a radius of 2. Of course I'm assuming that dΘ is from 0 to 2pi. I tried integrating with dr from 0 to 2 and from 2 to 4, but both times the answer was different than Wolfram's.