Top view of the cylinder. O is at the center. ABCD is the upper circle, and WXYZ are located directly underneath these. The side view of the cylinder appears as a square, because the diameter AC is equal to the height AW. Now, imagine truncating the solid by planes BDW and BDY, leaving the triangle shown in the lower right. The solid that remains will pass through and plug a circle (its base WXYZ is a circle), a square (using square DBXZ), and a triangle (BWY) whose height is equal to its base.