The figure is made up of a circle, a rectangle and 2 semicircles. YA, the diameter of the circle, is 75 cm, YZ is 72 cm and ZA is 21 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 YZ
= 72 ÷ 2 
= 36 cm

Area of Semicircle YZ
= ¹₂ x 36 x 36 x 3.14
= 2034.72 cm²

Radius of ZA
= 21 ÷ 2
= 10.5 cm

Area of Semicircle ZA
= ¹₂ x 10.5 x 10.5 x 3.14
= 173.0925 cm²

Radius of YA
= 75 ÷ 2
= 37.5 cm

Area of the semicircle YA = Radius YA
= ¹₂ x 37.5 x 37.5 x 3.14
= 2207.8125 cm²

Total area of shaded parts
= 2034.72 + 173.0925 + ¹₂ x 72 x 21 - 2207.8125
= 756 cm²

(b)
Length of Semicircle YZ
= ¹₂ x 3.14 x 72
= 113.04 cm

Length of Semicircle ZA
= ¹₂ x 3.14 x 21
= 32.97 cm

Length of Semicircle YA
= ¹₂ x 3.14 x 75
= 117.75 cm

Perimeter of shaded parts
= 113.04 + 32.97 + 117.75 
= 2034.72 cm

Answer(s): (a) 756 cm²; (b) 2034.72 cm