PSLE A symmetric figure is drawn on a rectangular piece of paper 24 cm by 16 cm as shown. Its outline consists of a large semicircle, 3 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
= 24 ÷ 2
= 12 cm
Area of the large semicircle
=
12 x 3.14 x 12 x 12
= 226.08 cm
2 Breadth of the small rectangle
= 16 - 12
= 4 cm
Area of the small rectangle
= 24 x 4
= 96 cm
2 Area of the 3 smaller semicircles
= 1.5 x 3.14 x 4 x 4
= 75.36 cm
2 Area of the 6 boomerangs
= 96 - 75.36
= 20.64 cm
2 Area of the figure
= 20.64 + 226.08
= 246.72 cm
2 (b)
Circumference of the curved lines
= 3.14 x 24
= 75.36 cm
Perimeter of the figure
= 75.36 + 4 + 4
= 83.36 cm
Answer(s): (a) 246.72 cm
2; (b) 83.36 cm