Question

Find the area of a circle whose radius is

(i) 21 cm.
(ii) 3.5 m.

Answer 1

(i) Given:
r = 21 cm

∴ Area of the circle = $\left({\mathrm{\pi r}}^2\right)$ sq. units
= $\left(\frac{22}{7}\times 21\times 21\right)$ cm² = $\left(22\times 3\times 21\right)$ cm² = 1386 cm²

(ii) Given:
r = 3.5 m

Area of the circle = $\left({\mathrm{\pi r}}^2\right)$ sq. units
= $\left(\frac{22}{7}\times 3.5\times 3.5\right)$ m² = $\left(22\times 0.5\times 3.5\right)$ m² = 38.5 m²