Question

Find the radius and area of a circle, whose circumference is :

(i) 132 cm

(ii) 22 m

Answer 1

Circumference of circle =132 cm

$\therefore 2\pi r=132$

$2\times \frac{22}{7}\times r=132$

$r=\frac{132\times 7}{2\times 22}$

r =21 cm

$\therefore$ Area of circle $=\pi r^2$

$=\frac{22}{7}\times 21\times 21$

$=1386c{m}^2$

(ii)Circumference of circle =22 m

$\therefore 2\pi r=22$

$2\times \frac{22}{7}\times r=22$

$r=\frac{22\times 7}{2\times 22}$

$r=\frac{7}{2}$

r =3.5 m

Area of circle $=\pi r^2$

$=\frac{22}{7}\times 3.5\times 3.5$

$=38.5m^2$