I need to show that ds^2 = dx^ + dy^2 + dz^2 is the same as ds^2 = dr^2 + r^2 (dpheta^2 + sin^2pheta*dphi^2) .... I know that I need to use x = r sin pheta cos phi y = r sin pheta sin phi z = r cos pheta I am confused but I think I have to take the derivitive of something. Do I somehow take the partial derivitives and if so of what? Can someone point me in the right direction. Thank you!