PSLE A symmetric figure is drawn on a rectangular piece of paper 64 cm by 40 cm as shown. Its outline consists of a large semicircle, 4 smaller semicircles and 2 straight lines.
- What is the area of the figure?
- What is its perimeter? Take π = 3.14
(a)
Radius of the large semicircle
= 64 ÷ 2
= 32 cm
Area of the large semicircle
=
12 x 3.14 x 32 x 32
= 1607.68 cm
2 Breadth of the small rectangle
= 40 - 32
= 8 cm
Area of the small rectangle
= 64 x 8
= 512 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 8 x 8
= 401.92 cm
2 Area of the 8 boomerangs
= 512 - 401.92
= 110.08 cm
2 Area of the figure
= 110.08 + 1607.68
= 1717.76 cm
2 (b)
Circumference of the curved lines
= 3.14 x 64
= 200.96 cm
Perimeter of the figure
= 200.96 + 8 + 8
= 216.96 cm
Answer(s): (a) 1717.76 cm
2; (b) 216.96 cm