Question

Radii of the circles are given below, find their areas.
(1) 28 cm
(2) 10.5 cm
(3) 17.5 cm

Answer 1

(1) 28 cm
$$\begin{gathered} \mathrm{Ar}=\mathrm{\pi }{r}^2=\mathrm{\pi }\times {\left(28\right)}^2 \\ =\frac{22}{7}\times 28\times 28 \\ =2464\mathrm{sq}\mathrm{cm} \end{gathered}$$

(2) 10.5 cm
$$\begin{gathered} \mathrm{Ar}=\mathrm{\pi }{r}^2=\mathrm{\pi }\times {\left(10.5\right)}^2 \\ =\frac{22}{7}\times 10.5\times 10.5 \\ =346.5\mathrm{sq}\mathrm{cm} \end{gathered}$$

(3) 17.5 cm
$$\begin{gathered} \mathrm{Ar}=\mathrm{\pi }{r}^2=\mathrm{\pi }\times {\left(17.5\right)}^2 \\ =\frac{22}{7}\times 17.5\times 17.5 \\ =962.5\mathrm{sq}\mathrm{cm} \end{gathered}$$