Question

A park is in the form of a rectangle 120 m by 90 m. At the centre of the park there is a circular lawn as shown in the figure. The area of the park excluding the lawn is 2950 m². Find the radius of the circular lawn.

Answer 1

Area of the rectangle = l × b

= 120 × 90 

= 10800 sq. m

Area of the park excluding the lawn = 2950 m²

Area of the circular lawn = Area of the park --  Area of the park excluding the lawn

= 10800 - 2950

= 7850 m²

Area of the circular lawn =πr²

`=> 7850 = 22/7xx"r"^2`

`=> (7850) = 22/7xx"r"^2`

`=> "r"^2 = 2497.72`

⇒ r = 49.97

Or,

r ≈ 50 m

Thus, the radius of the circular lawn is 50 m.