Informal Arguments for Circle/Solid Formulas Practice Test

A circle is cut into many equal sectors and rearranged into an almost-rectangle by alternating the sectors. The height is the radius $r$, and the base is half the circumference. Which conclusion follows from the dissection shown that supports the formula $A=\pi r^2$?

A cone is sliced horizontally into many thin layers and rearranged (without stretching) into a stepped shape that approximates a prism-like solid. The rearrangement keeps each layer’s area the same and keeps the total height $h$. Which reasoning explains why this supports the cone volume formula $V=\tfrac13\pi r^2 h$?