So the area of the face of the washer, well, it could be the area if it wasn't gutted out, and what would that area be? Well, it would be pi times the overall, the outside radius squared. It would be pi times the outside radius squared. Well, what's the outside radius? The radius that goes to the outside of the washer. Well, that's f of x. So it's gonna be f of x is the radius, and we're just going to square that.