Now let's think about the area of this wedge that I am highlighting in this yellow color. So what fraction of the entire circle is this going to be? If I were to go all the way around the circle, it would be two pi radians. So this is theta over two piths of the entire circle, and we know the area of the circle. This is a unit circle. It has a radius one. So it would be times the area of the circle, which would be pi times the radius squared.