Question

in the given figure a semicircle is drawn with centre O as centre and AB as diameter . semicircles are drawn with AO & BO as diameter . if AB = 28 m find perimeter of shaded region

Answer 1

Here you go.
Comment if you don't understand anything.

Answer 2

to find the perimeter of the larger hemisphere- 2πr/2 = πr = 44 cm ( radius of larger hemisphere is 14 cm)
perimeters of two smaller hemispheres - 2×2πr /2 = 2πr = 44 cm ( radius of smaller hemispheres is 7 cm )
adding both we get 88cm as perimeter of the shaded region.
Hope it helps