I came across this calculus problem that asked me to find the volume of the ellipse (x^2)/9 + y^2 = 1 rotated around the line y = 5. What I don't understand is that before you even attempt the problem you have to shift it down 5 units so that the center is at (0, -5). My question is why do you have to shift it down 5 units. I got confused because in calculus when you rotate a function around a line you don't usually move the function anywhere, it stays in one spot.