And the area under this quarter circle, we can just use a little bit of geometry to figure that out. We know its radius. The radius here is three. Radius is equal to three. The entire circle is pi r squared. So the entire circle, the area if this was an entire circle right over here, if this was an entire circle, that area would be pi r squared, so pi times three squared, so nine pi. So it would be nine pi, but this is only 1 1⁄4 of the entire circle, so we wanna divide it by four.