Question

The area of a circle is $38.5{\text{cm}}^2$. Its circumference is

• A. $62\text{cm}$
• B. $12.1\text{cm}$
• C. $11\text{cm}$
• D. $22\text{cm}$

Answer 1

The correct option is D $22\text{cm}$

Area of circle $=\pi r^2$
$\therefore 38.5=\pi r^2$
$\frac{22}{7}{r}^2=38.5$
$r^2=38.5\times \frac{7}{22}$
$r^2=12.25$
$r=\sqrt{12.25}$
$r=3.5$
Now, circumference of circle $=2\times \pi r$
$\therefore$ Circumference of circle $=2\times \frac{22}{7}\times \frac{35}{10}$
$\therefore$ Circumference of circle $=22\text{m}$