PSLE A symmetric figure is drawn on a rectangular piece of paper 132 cm by 88 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
= 132 ÷ 2
= 66 cm
Area of the large semicircle
=
12 x 3.14 x 66 x 66
= 6838.92 cm
2 Breadth of the small rectangle
= 88 - 66
= 22 cm
Area of the small rectangle
= 132 x 22
= 2904 cm
2 Area of the 3 smaller semicircles
= 1.5 x 3.14 x 22 x 22
= 2279.64 cm
2 Area of the 6 boomerangs
= 2904 - 2279.64
= 624.36 cm
2 Area of the figure
= 624.36 + 6838.92
= 7463.28 cm
2 (b)
Circumference of the curved lines
= 3.14 x 132
= 414.48 cm
Perimeter of the figure
= 414.48 + 22 + 22
= 458.48 cm
Answer(s): (a) 7463.28 cm
2; (b) 458.48 cm