PSLE A symmetric figure is drawn on a rectangular piece of paper 174 cm by 116 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
= 174 ÷ 2
= 87 cm
Area of the large semicircle
=
12 x 3.14 x 87 x 87
= 11883.33 cm
2 Breadth of the small rectangle
= 116 - 87
= 29 cm
Area of the small rectangle
= 174 x 29
= 5046 cm
2 Area of the 3 smaller semicircles
= 1.5 x 3.14 x 29 x 29
= 3961.11 cm
2 Area of the 6 boomerangs
= 5046 - 3961.11
= 1084.89 cm
2 Area of the figure
= 1084.89 + 11883.33
= 12968.22 cm
2 (b)
Circumference of the curved lines
= 3.14 x 174
= 546.36 cm
Perimeter of the figure
= 546.36 + 29 + 29
= 604.36 cm
Answer(s): (a) 12968.22 cm
2; (b) 604.36 cm