Question

what will be the area of a semi circle whose perimeter is 36 cm

Answer 1

Hi ,

Let the radius of a semicircle = r cm

Perimeter of the semicircle = π r + 2r

P = 36

r( π + 2 ) = 36

r ( 22/7 + 2 ) = 36

r ( 22 + 14 )/7

(36/7)r = 36

r = ( 36 × 7 )/36

r = 7 cm

Area of the semicircle = π r²/2

A = ( 22/7 ) × 7 × 7/2

A = ( 22 × 7 ) /2

A = 11 × 7

A = 77 cm²

I hope this helps you.

: )

Answer 2

Hey

Here is your answer,

Perimeter of semi circle = πr + 2r
22/7 x r + 2 x r = 36
22r/7 + 2r = 36
2(11r/7 + r) =36
11r/7 + r = 18
11r + 7r = 18x7
18r = 126
R=126/18
= 7 cm

Area of semi circle = 1/2 x πr ^2
= 1/2 x 22/7 x 7 x 7
= 11 x 7cm = 77cm

Hope it helps you!