Find the circumference and area of a circle of radius 4.2 cm.

Given:

A circle of radius 4.2 cm.
To do:

We have to find the circumference and area of the circle.

Solution:

We know that,

Circumference of a circle of radius $r=2 \pi r$

Area of a circle of radius $r=\pi r^2$

Therefore,

Circumference of the given circle $=2 \times \frac{22}{7} \times 4.2$

$=26.4 \mathrm{~cm}$

Area of the given circle $=\frac{22}{7} \times(4.2)^{2} \mathrm{cm}^{2}$

$=\frac{22}{7} \times 4.2 \times 4.2 \mathrm{~cm}^{2}$

$=55.44 \mathrm{~cm}^{2}$

The circumference and area of the circle are $26.4\ cm$ and $55.44\ cm^2$.