PSLE A symmetric figure is drawn on a rectangular piece of paper 136 cm by 102 cm as shown. Its outline consists of a large semicircle, 2 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
= 136 ÷ 2
= 68 cm
Area of the large semicircle
=
12 x 3.14 x 68 x 68
= 7259.68 cm
2 Breadth of the small rectangle
= 102 - 68
= 34 cm
Area of the small rectangle
= 136 x 34
= 4624 cm
2 Area of the 2 smaller semicircles
= 3.14 x 34 x 34
= 3629.84 cm
2 Area of the 4 boomerangs
= 4624 - 3629.84
= 994.16 cm
2 Area of the figure
= 994.16 + 7259.68
= 8253.84 cm
2 (b)
Circumference of the curved lines
= 3.14 x 136
= 427.04 cm
Perimeter of the figure
= 427.04 + 34 + 34
= 495.04 cm
Answer(s): (a) 8253.84 cm
2; (b) 495.04 cm