PSLE A symmetric figure is drawn on a rectangular piece of paper 56 cm by 42 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
= 56 ÷ 2
= 28 cm
Area of the large semicircle
=
12 x 3.14 x 28 x 28
= 1230.88 cm
2 Breadth of the small rectangle
= 42 - 28
= 14 cm
Area of the small rectangle
= 56 x 14
= 784 cm
2 Area of the 2 smaller semicircles
= 3.14 x 14 x 14
= 615.44 cm
2 Area of the 4 boomerangs
= 784 - 615.44
= 168.56 cm
2 Area of the figure
= 168.56 + 1230.88
= 1399.44 cm
2 (b)
Circumference of the curved lines
= 3.14 x 56
= 175.84 cm
Perimeter of the figure
= 175.84 + 14 + 14
= 203.84 cm
Answer(s): (a) 1399.44 cm
2; (b) 203.84 cm