I am attempting to use integration to determine the formula for the volume of three dimensional shapes for the sake of practice. My issue is I really lack the skills to determine what type of two-dimensional rotations will obtain a shape. The only one I have been able to do so far has been rotating a semi-circle over an axis to obtain a sphere. Sorry if this is confusing, I'm not sure how to phrase myself. Better yet, I wasn't sure whether to post this in the calculus or geometry section.