PSLE A symmetric figure is drawn on a rectangular piece of paper 184 cm by 115 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
= 184 ÷ 2
= 92 cm
Area of the large semicircle
=
12 x 3.14 x 92 x 92
= 13288.48 cm
2 Breadth of the small rectangle
= 115 - 92
= 23 cm
Area of the small rectangle
= 184 x 23
= 4232 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 23 x 23
= 3322.12 cm
2 Area of the 8 boomerangs
= 4232 - 3322.12
= 909.88 cm
2 Area of the figure
= 909.88 + 13288.48
= 14198.36 cm
2 (b)
Circumference of the curved lines
= 3.14 x 184
= 577.76 cm
Perimeter of the figure
= 577.76 + 23 + 23
= 623.76 cm
Answer(s): (a) 14198.36 cm
2; (b) 623.76 cm