Question

The radius of a circular grass field is 35m. A 7 m wide road runs round outside the field. Find the area of the road.

Answer 1

Radius of the circular grass field is $r_1=35m$

A $7m$ wide road runs round outside the field as shown in the figure.

So radius of the bigger circle is $r_2=35+7=42m$

We can find the area of the road by subtracting the area of the grass field from the area of bigger circle.

So, area of the road $=\pi (r_2{)}^2-\pi (r_1{)}^2$

$=\pi (42{)}^2-\pi (35{)}^2$

$=539\pi$

$=539\times \frac{22}{7}=1694m^2$