I'm doing a little self tutoring here, but I'm having trouble finding centroids for geometric shapes. I have a book that gives the formula for x and y coordinates (something like x = int(x dA)/int(dA) and similar for y). I still don't understand it though. Can someone explain it in more detail or link me to somewhere where they do that? A simple example would help, something like finding the centroid of a 3x2 rectangle with a corner at the origin using the calculus formulas. I think once I understand a simple case I'll be able to do more complicated ones. Thanks!