PSLE The figure is formed by two identical circles at K and M. KMLN is a square and the length of LM is 7 cm. (Take π = 3.14)
- Find the perimeter of the unshaded part.
- Find the total area of the shaded parts.
(a)
Diameter of the circle
= 2 x 7
= 14 cm
Perimeter of the unshaded part
=
12 x 3.14 x 14
= 21.98 cm
(b)
Area of the unshaded part
= Area of the semicircle - Area of the triangle
=
12 x 3.14 x 7 x 7 -
12 x 14 x 7
= 76.93 - 49
= 27.93 cm
2 Area of the circle
= 3.14 x 7 x 7
= 153.86 cm
2 Total area of the shaded parts
= 2 x (Area of the circle - Area of unshaded part)
= 2 x (153.86 - 27.93)
= 2 x 125.93
= 251.86 cm
2 Answer(s): (a) 21.98 cm; (b) 251.86 cm
2