Figure $P1.6$ shows a frustum of a cone. Match each of the three expressions $(\mathrm{a})\pi \left(r_1+r_2\right)[h^2+$\left.\left(r_{2}-r_{1}\right)^{2}\right]^{1 / 2},$(b)$2 \pi\left(r_{1}+r_{2}\right),$and(c)$\pi h\left(r_{1}^{2}+r_{1} r_{2}+r_{2}^{2}\right) / 3$ with the quantity it describes: (d) the total circumference of the flat circular faces, (e) the volume, or (f) the area of the curved surface.

Key Concepts: Frustum Of A Cone, Circumference, Volume, Curved Surface Area Explanation: To match the expressions with the correct quantity, we need to identify what each expression represents. Expression (a) involves the slant height and radii of the frustum. Expression (b) involves only the radii of the frustum. And expression (c) involves the height and radii of the frustum.\n Option (d) is the total circumference of the flat circular faces. Option (e) is the volume of the frustum. And option (f) is the area of the curved surface. Step by Step Solution: Step 1. Expression (a) involves the slant height and radii of the frustum. It gives us the value of the curved surface area. Step 2. Expression (b) involves only the radii of the frustum. It gives us the value of the total circumference of the flat circular faces. Step 3. Expression (c) involves the height and radii of the frustum. It gives us the value of the volume of the frustum. Final Answer: (a) describes the area of the curved surface, (b) describes the total circumference of the flat circular faces, and (c) describes the volume of the frustum.