PSLE A symmetric figure is drawn on a rectangular piece of paper 136 cm by 85 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
= 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
= 85 - 68
= 17 cm
Area of the small rectangle
= 136 x 17
= 2312 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 17 x 17
= 1814.92 cm
2 Area of the 8 boomerangs
= 2312 - 1814.92
= 497.08 cm
2 Area of the figure
= 497.08 + 7259.68
= 7756.76 cm
2 (b)
Circumference of the curved lines
= 3.14 x 136
= 427.04 cm
Perimeter of the figure
= 427.04 + 17 + 17
= 461.04 cm
Answer(s): (a) 7756.76 cm
2; (b) 461.04 cm