Question

The length of a chain used as a boundary of a semicircle park is 90m. Find the area of the park.

Answer 1

Perimeter of a semicircle is the sum of half of the perimeter of the circle and the diameter itself. If r and d be the redius and diameter of the semicircle then,
1/2(2πr)+d=90
or, πd+d=90
or, d(22/7+1)=90
or, d{(22+7)/7}=90
or, d=90×7/29
or, d=21.724cm
∴, r=21.724/2=10.862cm
∴, area of the semicircular park
=1/2(πr²)
=1/2×22/7×(10.862)²
=11/7×117.983
=185.402cm² Ans.

Answer 2

the solution is 481.25 m2