PSLE The figure shows 4 circles, each of radius 24.5 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 24.5
= 49 cm
Perimeter of the shaded part
= Circumference of 2 circles
= 2 x
227 x 49
= 308 cm
(b)
Length of the dotted square
= Diameter of each circle
= 49 cm
Area of the dotted square
= 49 x 49
= 2401 cm
2 Area of 1 circle
=
227 x 24.5 x 24.5
= 1886.5 cm
2 Area of the shaded part
= 2401 + 1886.5
= 4287.5 cm
2 Answer(s): (a) 308 cm; (b) 4287.5 cm
2