If we think about the volume of the outer shape, once again, we can use the disk method. So at any given point in time, our radius for one of our disks is going to be equal to the function. Let's rotate that disk around. Actually, let me do it in a different color. It's hard to see that disk, since it's in the same magenta. So this is our radius, and let's rotate it around. So I'm rotating the disk around.