PSLE A symmetric figure is drawn on a rectangular piece of paper 200 cm by 125 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
= 200 ÷ 2
= 100 cm
Area of the large semicircle
=
12 x 3.14 x 100 x 100
= 15700 cm
2 Breadth of the small rectangle
= 125 - 100
= 25 cm
Area of the small rectangle
= 200 x 25
= 5000 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 25 x 25
= 3925 cm
2 Area of the 8 boomerangs
= 5000 - 3925
= 1075 cm
2 Area of the figure
= 1075 + 15700
= 16775 cm
2 (b)
Circumference of the curved lines
= 3.14 x 200
= 628 cm
Perimeter of the figure
= 628 + 25 + 25
= 678 cm
Answer(s): (a) 16775 cm
2; (b) 678 cm