We don't want just the area of s. We're saying that s is the base. And if we take a cross section, we're going to have squares. So this is going to be a base of a square. So this length right over here is going to be the absolute value of f of x minus g of x. That's the length of the base. But if we want the area of that cross section, you can imagine, let me draw it at a little bit of an angle here. So you have a cross section of a square there.