PSLE A symmetric figure is drawn on a rectangular piece of paper 48 cm by 30 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
= 48 ÷ 2
= 24 cm
Area of the large semicircle
=
12 x 3.14 x 24 x 24
= 904.32 cm
2 Breadth of the small rectangle
= 30 - 24
= 6 cm
Area of the small rectangle
= 48 x 6
= 288 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 6 x 6
= 226.08 cm
2 Area of the 8 boomerangs
= 288 - 226.08
= 61.92 cm
2 Area of the figure
= 61.92 + 904.32
= 966.24 cm
2 (b)
Circumference of the curved lines
= 3.14 x 48
= 150.72 cm
Perimeter of the figure
= 150.72 + 6 + 6
= 162.72 cm
Answer(s): (a) 966.24 cm
2; (b) 162.72 cm