Question

The surface area of the solid of hemispherical base of radius 7 cm surmounted by cone of slant height 7 cm is ____.

• A. 462 cm${}^2$
• B. 221 cm${}^2$
• C. 262 cm${}^2$
• D. 421 cm${}^2$

Answer 1

The correct option is A 462 cm${}^2$

Given,
Solid combination: Hemisphere + Cone
Radius of Cone and Hemisphere, $r=7\text{cm}$
Slant height of cone, $l=7\text{cm}$
$r=l$

Surface area of solid
= CSA of hemisphere + CSA of cone
$=2\pi r^2+\pi rl=2\pi r^2+\pi r^2=3\pi r^2=3\times \frac{22}{7}\times 7\times 7=462{\text{cm}}^2$