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Question

A circular park is surrounded by a road 21 m wide. If the radius of the park is 105 m, find the area of the road.

A
13860 m2
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B
30492 m2
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C
7623 m2
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D
15246 m2
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Solution

The correct option is D 15246 m2

O is the centre of a circular park of radius OA=105 m with a concentric surrounding circular road of width AB=21 m
To find the area of the road, first we need to find area of the park and then subtract the area of park from total area including road.
Let's find area of a park.
Park forms a circle with radius(r)=105 m
Area of the park =πr2=π(105)2
The outer circle represents total area which includes park and road with radius(R)=105+21=126
Total area =πR2=π(126)2
Thus, area of the road = Total area Area of park
=π(126)2π(105)2=π(12621052)=4851π=15246 m2
Hence, area of road =15246 m2

221926_82810_ans.png

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