In figure 7, a semi-circle is drawn with O as center and AB as diameter. Semi-circles are drawn with AO and OB as diameters. If AB = 28 m, find the perimeter of the shaded region. [Use π = 22/7].

Given: Diameter of the larger semi-circle = 28 cm

Radius of the larger circle = AB = R = 14 cm

∴ Radius of the smaller circles = OA = OB = r = 28/4 = 7 cm

Perimeter of the shaded region = πR + πr + πr

= π [14 + 7 + 7]

= (22/7) × (28)

= 22 × 4

= 88

Therefore, perimeter of the shaded region = 88 cm