So that is one minus x over two is equal to the radius. And so what would be the area of, what would be the area of this side right over here? Well, if it was a full circle, it would be pi r squared, but it's a semicircle, so it's pi r squared over two. So let me write this. So the area is equal to pi r squared, r squared over two, because it's a semicircle. So in terms of x, I guess I could say our area as a function of x right over there. Let me write it that way.