Let us evaluate
where is the solid wedge in the first actant cut from the cylindrical solid by the planes and .
The region can be written as
where is the projection of the wedge on the -plane and is given by
is the solid wedge in the first actant cut from the cylindrical solid 
by the planes 
and 
. 
and its projection 
onto 
-plane 
can be written as 
-plane and is given by 
