PSLE
The figure is made up of 6 identical quadrants and 2 identical semicircles. The radius of each quadrant is 20 cm. The unshaded area marked A is enclosed by 2 quadrants and 2 semicircles. (Take π = 3.14)

1. Find the perimeter of V.
2. Find the total shaded areas.

(a)
Perimeter of 2 semicircles
= 3.14 x 20
= 62.8 cm

Diameter of the quadrant
= 2 x 20
= 40 cm

Perimeter of 2 quadrants
= ¹₂ x 3.14 x 40
= 62.8 cm

Perimeter of V
= 62.8 + 62.8
= 125.6 cm

(b)
Area of the large circle
= 3.14 x 20 x 20
= 1256 cm²

Area of 2 semicircles
= 3.14 x 10 x 10
= 314 cm²

Area of 2 boomerangs
= Area of the rectangle - Area of the semicircle
= 40 x 20 - ¹₂ x 3.14 x 20 x 20
= 800 - 628
= 172 cm²

Total shaded areas
= 1256 - 314 - 172
= 770 cm²

Answer(s): (a) 125.6 cm; (b) 770 cm²