Stewart, Early Transcendentals, 6.2, problem 54: find volume of solid - base S is a circular disc with radius R. Parallel cross-sections perpendicular to base are squares. I did it 2 ways, and got different answers. First one goes along with the chapter examples, and I think is fine. Second one (integrating with respect to angle theta) seems like it should work, but different answer. Where do I go wrong? thanks