Question

find the surface area of a sphere of radius 21cm​

Answer 1

$a = \frac{4}{3} \pi \: {r}^{2} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ a = \frac{4}{3} \times \frac{22}{7} \times 21 \times 21 \\ \\ a = 4 \times 22 \times 21 \: \: \: \: \: \: \: \: \: \: \: \\ \\ \pink{ \huge{ \bold{ \boxed{a = 2112}}}}$

PLEASE MARK ME AS BRAINLIST

Answer 2

Surface area of sphere formula = $4\pi r^{2}$

Substituting r as 21 cm.

Surface area = $4\pi (21)^{2}$

$=$ $4 *\frac{22}{7}*21*21$

$=5544$  $cm^{2}$