PSLE A symmetric figure is drawn on a rectangular piece of paper 104 cm by 78 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
= 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
= 78 - 52
= 26 cm
Area of the small rectangle
= 104 x 26
= 2704 cm
2 Area of the 2 smaller semicircles
= 3.14 x 26 x 26
= 2122.64 cm
2 Area of the 4 boomerangs
= 2704 - 2122.64
= 581.36 cm
2 Area of the figure
= 581.36 + 4245.28
= 4826.64 cm
2 (b)
Circumference of the curved lines
= 3.14 x 104
= 326.56 cm
Perimeter of the figure
= 326.56 + 26 + 26
= 378.56 cm
Answer(s): (a) 4826.64 cm
2; (b) 378.56 cm