So the first thought that occured to me was to use a surface integral I got 2pi*a^2, which is half the SA, if I used the surface integral is it possible or likely that I just found half the SA and can then multiply by 2? Or something. Actually, I think I see what I did, for my sec(gamma) I used the sphere and am pretty sure I did that stuff right, then(I converted to polar coordinates)I did r from 0-a, and theta from 0-2pi, which would be the circular region ON the xy plane, and would give me half the SA, right? Maybe? Please? heh, but the big problem is the next part, find the centroid of the curved surface area of a hemisphere hur?