So the way I'd like to think about it, let's think about what the volume, if I were to just take the bottom function, if I were to just take f of x, if I were to just take f of x, and if I were to rotate that function around y equals x, if I were to rotate this thing around, sorry, around y is equal to one, what would the volume of that be? And then I'm going to subtract from that the volume if I were to take the top function, if I were to take g of x and rotate it around. So let's first of all think about what volume I would get, and this is really the disk method, and I go into it in much more detail earlier in the calculus playlist. But let's think about the volume if f of x is rotated around that axis. And to do that, let's imagine each sliver of that volume. So this is, let me draw a little thing right over here. And you can imagine once this little sliver is rotated, it forms, it forms, or you can imagine this length is the radius of a disk.