Finding the volume using double integrals Find the volume  of the wedge sliced from the cylinder $x^2+y^2 =1$ by the planes $z=a(2-x)$ and $z=a(x-2)$  $a>0$
I am confused because $x^2+y^2 = 1$ is a unit circle not a cylinder. and the other two are lines in the $zx$ plane where $y=0$. I don't see how they are planes, are they planes or are they just lines in the $zx$ plane (when $y=0$). I tried drawing the 3d picture but it made no sense since a cylinder wasn't formed.

Notice that there are many x-y planes (see graphic).

