Question

Find the area of the circle whose circumference is $77cm$ .$\left(take\pi =\frac{22}{7}\right)$

Answer 1

$2\pi r=77cm$ = circumference

$=2\times \frac{22}{7}\times r=77$

$r=\frac{77\times 7}{22\times 2}=\frac{49}{4}$ cm

Area $=\pi r^2=\frac{22}{7}\times \frac{49}{4}\times \frac{49}{4}$

$=\frac{11\times 7\times 49}{8}=\frac{3775}{8}=471.625c{m}^2$