So depth dx, that's the side of this washer. So a washer, you can imagine, is kind of a gutted out, it's a gutted out coin. It's a gutted out coin. So how do we find the volume? Well, once again, if we know the surface, if we know the area of the face of this washer, we can just multiply that times the depth. So it's gonna be the area of the face of the washer. 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?