A park is in the form of a rectangle 120m×100m. At the centre of the park there is a circular lawn. The area of park excluding lawn is 8700m2. Find the radius of the circular lawn.
Total area of rectangular park = 120×100 = 12000 m2
Area of park excluding circular lawn = 8700m2
So,
Area of circular lawn = 1200 – 8700 = 3300m2
= πr2 = 3300
r = 32.40 m