Question

find the area of the circle whose radius is
a)21 cm
b) 3.5 cm​

Answer 1

(a) 21

Area of a circle=πr²

so,22/7×21×21

=1385.44cm²

(b)3.5

area of circle=πr²

=22/7×3.5×3.5

=38.48 cm²

Answer 2

Answer:

$area \: of \: circle \: = {\pi}r^{2} \\ \pi = \frac{22}{7} \\ 1) \frac{22}{7} \times {21}^{2} cm \\ = 22 \times {3}^{2} \\ = 66 {cm}^{2} \\ 2)3.5 \: \: \: \: \: \: \: cm \\ \frac{22}{7} \times 3.5 {cm}^{2} \\ = 22 \times 0.5 {cm}^{2} \\ = 11.0 {cm}^{2} \\ = 11 {cm}^{2}$