1. The problem statement, all variables and given/known data Use Pappus' Theorem for surface area and the fact that the surface area of a sphere of radius c is 4(pi)c^2 to find the centroid of the semicircle x= sqrt ( c^2 - y^2) 2. Relevant equations S = 2 (pi) * p * L where s=surface area; p=distance from axis of revolution; L= length of the arc 3. The attempt at a solution 1. centroid of semicircle. should i put the equation in circle form, and attempt to solve from that?