Well, our radius right over here is going to be f of y. It's going to be the square root of y. So it's going to be a function of y. I don't want to confuse you if you thought this was f of x and I'm saying this is f of y. It's going to be a function of y. We could call it g of y. It's going to be the square root of y. So area is equal to pi r squared, which means that the area of this thing is going to be pi times our radius squared.