We're going to construct a disk right over there that has the same radius of the shape at that point. So that's our disk right over here. And then it has a depth. Instead of saying it has a depth of dx, let's say it has a depth of dy. So this depth right over here is dy. So what is the volume of this disk in terms of y? And as you can imagine, we're going to do this definite integral with respect to y.