The figure is made up of a circle, a rectangle and 2 semicircles. ZB, the diameter of the circle, is 10 cm, ZA is 8 cm and AB is 6 cm.

1. What is the total area of the shaded parts?
2. What is the total perimeter of the shaded parts? (Take π = 3.14)

(a)
Radius of ZA
= 8 ÷ 2 
= 4 cm

Area of Semicircle ZA
= ¹₂ x 4 x 4 x 3.14
= 25.12 cm²

Radius of AB
= 6 ÷ 2
= 3 cm

Area of Semicircle AB
= ¹₂ x 3 x 3 x 3.14
= 14.13 cm²

Radius of ZB
= 10 ÷ 2
= 5 cm

Area of the semicircle ZB = Radius ZB
= ¹₂ x 5 x 5 x 3.14
= 39.25 cm²

Total area of shaded parts
= 25.12 + 14.13 + ¹₂ x 8 x 6 - 39.25
= 24 cm²

(b)
Length of Semicircle ZA
= ¹₂ x 3.14 x 8
= 12.56 cm

Length of Semicircle AB
= ¹₂ x 3.14 x 6
= 9.42 cm

Length of Semicircle ZB
= ¹₂ x 3.14 x 10
= 15.7 cm

Perimeter of shaded parts
= 12.56 + 9.42 + 15.7 
= 25.12 cm

Answer(s): (a) 24 cm²; (b) 25.12 cm