PSLE A symmetric figure is drawn on a rectangular piece of paper 156 cm by 104 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
= 156 ÷ 2
= 78 cm
Area of the large semicircle
=
12 x 3.14 x 78 x 78
= 9551.88 cm
2 Breadth of the small rectangle
= 104 - 78
= 26 cm
Area of the small rectangle
= 156 x 26
= 4056 cm
2 Area of the 3 smaller semicircles
= 1.5 x 3.14 x 26 x 26
= 3183.96 cm
2 Area of the 6 boomerangs
= 4056 - 3183.96
= 872.04 cm
2 Area of the figure
= 872.04 + 9551.88
= 10423.92 cm
2 (b)
Circumference of the curved lines
= 3.14 x 156
= 489.84 cm
Perimeter of the figure
= 489.84 + 26 + 26
= 541.84 cm
Answer(s): (a) 10423.92 cm
2; (b) 541.84 cm