Question

Find the perimeter and area of semicircles whose diameters are,

(i) 2.8 cm (ii) 56 cm (iii) 84 cm (iv) 112 m

Answer 1

Perimeter of semicircle = πR
Area = πr^2/2
1) perimeter = π×2.8/2 = 1.4π cm
area = 1.96π cm^2
2) perimeter = 28π
area = π28×28 cm^2

Answer 2

1. per. = πr
= π × 1.4
=1.4π cm
area = πr2/2
= π×1.4×1.4/2
= π ×0.98
=0.98πcm2
2. per. =π×28
=28πcm
area = π × 28×28/2
= 392πcm2
3. per. = π×42
=42πcm
area = π× 42×42/2
=882 π cm2