PSLE A symmetric figure is drawn on a rectangular piece of paper 96 cm by 64 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
= 96 ÷ 2
= 48 cm
Area of the large semicircle
=
12 x 3.14 x 48 x 48
= 3617.28 cm
2 Breadth of the small rectangle
= 64 - 48
= 16 cm
Area of the small rectangle
= 96 x 16
= 1536 cm
2 Area of the 3 smaller semicircles
= 1.5 x 3.14 x 16 x 16
= 1205.76 cm
2 Area of the 6 boomerangs
= 1536 - 1205.76
= 330.24 cm
2 Area of the figure
= 330.24 + 3617.28
= 3947.52 cm
2 (b)
Circumference of the curved lines
= 3.14 x 96
= 301.44 cm
Perimeter of the figure
= 301.44 + 16 + 16
= 333.44 cm
Answer(s): (a) 3947.52 cm
2; (b) 333.44 cm