1. The problem statement, all variables and given/known data Find the mass of a spherical surface S of radius R such that at each point (x, y, z) in S the mass density is equal to the distance of (x, y, z) to some fixed point (x_0, y_0, z_0) in S. 2. Relevant equations Integral of a scalar function over a surface. 3. The attempt at a solution I was thinking about converting this into spherical coordinates, but I see no way of doing that nicely since the distance formula would get very messy. I am also assuming they are using the euclidean distance, since this is an intro multivariable course. I don't need help evaluating, just with getting it set up. This is from Vector Calculus, 5e. by Marsden and Tromba, 7.5 #9.