PSLE A symmetric figure is drawn on a rectangular piece of paper 114 cm by 76 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
= 114 ÷ 2
= 57 cm
Area of the large semicircle
=
12 x 3.14 x 57 x 57
= 5100.93 cm
2 Breadth of the small rectangle
= 76 - 57
= 19 cm
Area of the small rectangle
= 114 x 19
= 2166 cm
2 Area of the 3 smaller semicircles
= 1.5 x 3.14 x 19 x 19
= 1700.31 cm
2 Area of the 6 boomerangs
= 2166 - 1700.31
= 465.69 cm
2 Area of the figure
= 465.69 + 5100.93
= 5566.62 cm
2 (b)
Circumference of the curved lines
= 3.14 x 114
= 357.96 cm
Perimeter of the figure
= 357.96 + 19 + 19
= 395.96 cm
Answer(s): (a) 5566.62 cm
2; (b) 395.96 cm