Exercises: Informal Arguments for Sphere Volume Using Cavalieri's Principle

For the cylinder-minus-cone comparison solid (cylinder radius $r$, height $r$; cone apex at base, base radius $r$ at top), at height $h$ the cone's inner radius equals   ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲   . The annular cross-sectional area is $A_{\text{annulus}}(h) =$   ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲   .