PSLE A symmetric figure is drawn on a rectangular piece of paper 36 cm by 27 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
= 36 ÷ 2
= 18 cm
Area of the large semicircle
=
12 x 3.14 x 18 x 18
= 508.68 cm
2 Breadth of the small rectangle
= 27 - 18
= 9 cm
Area of the small rectangle
= 36 x 9
= 324 cm
2 Area of the 2 smaller semicircles
= 3.14 x 9 x 9
= 254.34 cm
2 Area of the 4 boomerangs
= 324 - 254.34
= 69.66 cm
2 Area of the figure
= 69.66 + 508.68
= 578.34 cm
2 (b)
Circumference of the curved lines
= 3.14 x 36
= 113.04 cm
Perimeter of the figure
= 113.04 + 9 + 9
= 131.04 cm
Answer(s): (a) 578.34 cm
2; (b) 131.04 cm