PSLE A symmetric figure is drawn on a rectangular piece of paper 104 cm by 65 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
= 104 ÷ 2
= 52 cm
Area of the large semicircle
=
12 x 3.14 x 52 x 52
= 4245.28 cm
2 Breadth of the small rectangle
= 65 - 52
= 13 cm
Area of the small rectangle
= 104 x 13
= 1352 cm
2 Area of the 4 smaller semicircles
= 2 x 3.14 x 13 x 13
= 1061.32 cm
2 Area of the 8 boomerangs
= 1352 - 1061.32
= 290.68 cm
2 Area of the figure
= 290.68 + 4245.28
= 4535.96 cm
2 (b)
Circumference of the curved lines
= 3.14 x 104
= 326.56 cm
Perimeter of the figure
= 326.56 + 13 + 13
= 352.56 cm
Answer(s): (a) 4535.96 cm
2; (b) 352.56 cm