Book: RS Aggarwal - Mathematics

Chapter: 18. Area of Circle, Sector and Segment

Subject: Maths - Class 10th

Q. No. 47 of Exercise 18A

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47
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. [Given, π = 3.14]

Given:

Length of the rectangular park = 120 m

Breadth of the rectangular park = 90 m

Area of the park excluding the circular lawn = 2950m2

Area of the rectangular park = length × breadth

= 120 × 90

= 10800m2

Area of circular lawn = Area of rectangular park – Area of park excluding the lawn

= 10800 – 2950

= 7850m2

Area of circle = πr2

7850 = 3.14 × r2

r2 = = 2500

r = √2500 = 50 m

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

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