PSLE The figure is formed by two identical circles at L and N. LNMP is a square and the length of MN is 56 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 56
= 112 cm
Perimeter of the unshaded part
=
12 x 3.14 x 112
= 175.84 cm
(b)
Area of the unshaded part
= Area of the semicircle - Area of the triangle
=
12 x 3.14 x 56 x 56 -
12 x 112 x 56
= 4923.52 - 3136
= 1787.52 cm
2 Area of the circle
= 3.14 x 56 x 56
= 9847.04 cm
2 Total area of the shaded parts
= 2 x (Area of the circle - Area of unshaded part)
= 2 x (9847.04 - 1787.52)
= 2 x 8059.52
= 16119.04 cm
2 Answer(s): (a) 175.84 cm; (b) 16119.04 cm
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