PSLE The figure shows 4 circles, each of radius 28 cm. Each circle touches the circles next to it.
(Take π =
227)
- Find the perimeter of the shaded part.
- Find the area of the shaded part.
(a)
Diameter of each circle
= 2 x 28
= 56 cm
Perimeter of the shaded part
= Circumference of 2 circles
= 2 x
227 x 56
= 352 cm
(b)
Length of the dotted square
= Diameter of each circle
= 56 cm
Area of the dotted square
= 56 x 56
= 3136 cm
2 Area of 1 circle
=
227 x 28 x 28
= 2464 cm
2 Area of the shaded part
= 3136 + 2464
= 5600 cm
2 Answer(s): (a) 352 cm; (b) 5600 cm
2