Question

Find the surface area of a frustum of cone given below: (Use $\pi$ = 3)

• A. 3,992 cm${}^2$
• B. 3,192 cm${}^2$
• C. 2,192 cm${}^2$
• D. 3,192 cm

Answer 1

The correct option is B 3,192 cm${}^2$

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

D = 4 cm, d = 5 cm, s = 50 cm

Diameter = radius/2

Radius, R = 8 cm, r = 10 cm

$=\pi (10+8)50+\pi {10}^2+8^2$

$=3\times (900+100+64)$

$=3\times (1,064)$

$=3,192c{m}^2$