PSLE A symmetric figure is drawn on a rectangular piece of paper 32 cm by 24 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
= 32 ÷ 2
= 16 cm
Area of the large semicircle
=
12 x 3.14 x 16 x 16
= 401.92 cm
2 Breadth of the small rectangle
= 24 - 16
= 8 cm
Area of the small rectangle
= 32 x 8
= 256 cm
2 Area of the 2 smaller semicircles
= 3.14 x 8 x 8
= 200.96 cm
2 Area of the 4 boomerangs
= 256 - 200.96
= 55.04 cm
2 Area of the figure
= 55.04 + 401.92
= 456.96 cm
2 (b)
Circumference of the curved lines
= 3.14 x 32
= 100.48 cm
Perimeter of the figure
= 100.48 + 8 + 8
= 116.48 cm
Answer(s): (a) 456.96 cm
2; (b) 116.48 cm