Question

The larger and smaller diameter of a cone is 14 m and 5 m. The slant height of the cone is 100 m. What is the surface area of a frustum of cone? (Use $\pi$ = 3).

• A. 13,052 m${}^2$
• B. 14,052 m${}^2$
• C. 15,052 m${}^2$
• D. 16,052 m${}^2$

Answer 1

The correct option is B 14,052 m${}^2$

Surface area of a frustum of cone = $\pi$(r + R)s + $\pi$r${}^2$ + $\pi$R${}^2$

SA = $\pi$(28 + 10)100 + $\pi$10${}^2$ + $\pi$28${}^2$

= $\pi$(38)100 + 100$\pi$ + 784$\pi$

= 3 $\times$ (3800 + 100 + 784)

= 3 $\times$ 4,684

= 14,052 m${}^2$