The radius of a circle is 3r. Then its area and circumference is

Given:

The radius of a circle is 3r.

To do:

We have to find the area and circumference.
Solution:
We know that,

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

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

Therefore,

Area of a circle of radius $3r=\pi (3r)^2$ 

$=\pi (9r^2)$

$=9\pi r^2$.

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

$=2(2)\pi r$

$=4\pi r$.