So the outer radius is 2 minus y squared. We want it as a function of y. 2 minus y squared. And then our inner radius is going to be equal to what? Well, that's going to be the difference, the horizontal distance between this vertical line and our inner function, our inner boundary. So it's going to be the horizontal distance between 2 and whatever x value this is. But this x value as a function of y is just the square root of y.