Well, what's the radius? Well, the radius is just the height of that original rectangle, and for any x, the height over here is going to be equal to f of x, and in this case, f of x is x squared. So over here, our radius is equal to x squared. So the area of the face for a particular x is going to be equal to pi times f of x squared. In this case, f of x is x squared. Now what's our volume going to be? Well, our volume is going to be our area times the depth here.