Question

The radius of a circle is 21 cm. Find the perimeter and area of a quadrant of the circle.

Answer 1

Radius of a circle, r = 21 cm
Perimeter of a quadrant, $P=(\frac{\pi }{2}+2)r$ units
$=(\frac{22}{7\times 2}+2)\times 21=(\frac{22}{14}+2)\times 21$
$P=\left(\frac{22+28}{14}\right)\times 21=\frac{50}{14}\times 21$
$=75cm$.
Area of a quadrant, $A=\frac{\pi r^2}{4}$ sq. units
$A=\frac{22}{7}\times \frac{21\times 21}{4}$
$=346.5c{m}^2$.