PSLE A symmetric figure is drawn on a rectangular piece of paper 96 cm by 60 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
= 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
= 60 - 48
= 12 cm
Area of the small rectangle
= 96 x 12
= 1152 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 12 x 12
= 904.32 cm
2 Area of the 8 boomerangs
= 1152 - 904.32
= 247.68 cm
2 Area of the figure
= 247.68 + 3617.28
= 3864.96 cm
2 (b)
Circumference of the curved lines
= 3.14 x 96
= 301.44 cm
Perimeter of the figure
= 301.44 + 12 + 12
= 325.44 cm
Answer(s): (a) 3864.96 cm
2; (b) 325.44 cm