PSLE A symmetric figure is drawn on a rectangular piece of paper 124 cm by 93 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
= 124 ÷ 2
= 62 cm
Area of the large semicircle
=
12 x 3.14 x 62 x 62
= 6035.08 cm
2 Breadth of the small rectangle
= 93 - 62
= 31 cm
Area of the small rectangle
= 124 x 31
= 3844 cm
2 Area of the 2 smaller semicircles
= 3.14 x 31 x 31
= 3017.54 cm
2 Area of the 4 boomerangs
= 3844 - 3017.54
= 826.46 cm
2 Area of the figure
= 826.46 + 6035.08
= 6861.54 cm
2 (b)
Circumference of the curved lines
= 3.14 x 124
= 389.36 cm
Perimeter of the figure
= 389.36 + 31 + 31
= 451.36 cm
Answer(s): (a) 6861.54 cm
2; (b) 451.36 cm