The diagram shows a hemisphere, a circular cone, and a circular cylinder with
heights and radii both equal to 9.
a. Sketch parallel cross-sections of each solid at height 3 above plane P.
b. The base of the hemisphere, the vertex of the cone, and the base of the
cylinder lie in base plane P. Sketch parallel cross-sectional disks of the
figures at a distance h from the base plane, and then describe how the areas of
the cross-sections are related.