Question

Find the curved surface area of a frustum cone whose larger and smaller radius is 20 and 5 cm. The slant height is 10 cm. (Use $\pi$ = 3.14)

• A. 765 $c{m}^2$
• B. 785 $c{m}^2$
• C. 826$c{m}^2$
• D. 459 $c{m}^2$

Answer 1

Answer: (B)

785 $c{m}^2$

Curved surface area of a frustum cone = $\pi$(r + R)s $\Rightarrow$ ?

= 3.14 $\times$ (5 + 20) $\times$ 10

= 3.14 $\times$ (25) $\times$ 10

Curved surface area of a frustum cone = 785 cm${}^2$