A park is in the form of rectangle 120m × 100m. At the centre of park there is a circular lawn.

Question

A park is in the form of rectangle 120m x 100m. At the centre of park there is a circular lawn. The area of park excluding lawn is 8700m2. Find the radius of circular lawn.

Answer 1

Dimensions of rectangular park length = 120m

Breath = 100m

Area of park = l x b

=120x100=12000m².

Let radius of circular lawn be r

Area of circular lawn = πr²

Area of remaining park excluding lawn = (area of park) – (area of circular lawn)

⇒ 8700 = 12000 – πr²

⇒ πr² = 12000 – 8700 = 3300

⇒ 22/7 x r²=3300

⇒ r²=150x7=1050

⇒ r = √1050=5√42 metres

∴ radius of circular lawn = 5√42 metres.