Question

The circumference of a circle with radius 21 cm is ​

Answer 1

$area = \pi {r}^{2}$

$\frac{22}{7} \times {21}^{2}$

$\frac{22}{7} \times 441$

$\frac{22}{1} \times 63$

$1386$

So, Your answer is 1386 square cm.

Answer 2

By using formula

Circumference of circle=$\pink\{2 pi r}$

Value of pi is 22/7 or 3.14

Circumference of circle=2 ×22/7×21

Circumference of circle=44/7 ×21

Circumference of circle=44×3

Circumference of circle=132 cm

$\pink{132 \ cm}$