PSLE A symmetric figure is drawn on a rectangular piece of paper 208 cm by 130 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
= 208 ÷ 2
= 104 cm
Area of the large semicircle
=
12 x 3.14 x 104 x 104
= 16981.12 cm
2 Breadth of the small rectangle
= 130 - 104
= 26 cm
Area of the small rectangle
= 208 x 26
= 5408 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 26 x 26
= 4245.28 cm
2 Area of the 8 boomerangs
= 5408 - 4245.28
= 1162.72 cm
2 Area of the figure
= 1162.72 + 16981.12
= 18143.84 cm
2 (b)
Circumference of the curved lines
= 3.14 x 208
= 653.12 cm
Perimeter of the figure
= 653.12 + 26 + 26
= 705.12 cm
Answer(s): (a) 18143.84 cm
2; (b) 705.12 cm