Question: The surface area of a sphere of radius 21 cm is
(a) 2772 cm2
(b) 1386 cm2
(c) 4158 cm2
(d) 5544 cm2
Solution:
(d) $5544 \mathrm{~cm}^{2}$
Surface area of sphere $=4 \pi r^{2}$
$=4 \times \frac{22}{7} \times 21 \times 21$
$=5544 \mathrm{~cm}^{2}$
