PSLE A symmetric figure is drawn on a rectangular piece of paper 116 cm by 87 cm as shown. Its outline consists of a large semicircle, 2 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
= 116 ÷ 2
= 58 cm
Area of the large semicircle
=
12 x 3.14 x 58 x 58
= 5281.48 cm
2 Breadth of the small rectangle
= 87 - 58
= 29 cm
Area of the small rectangle
= 116 x 29
= 3364 cm
2 Area of the 2 smaller semicircles
= 3.14 x 29 x 29
= 2640.74 cm
2 Area of the 4 boomerangs
= 3364 - 2640.74
= 723.26 cm
2 Area of the figure
= 723.26 + 5281.48
= 6004.74 cm
2 (b)
Circumference of the curved lines
= 3.14 x 116
= 364.24 cm
Perimeter of the figure
= 364.24 + 29 + 29
= 422.24 cm
Answer(s): (a) 6004.74 cm
2; (b) 422.24 cm