PSLE The figure is formed by two identical circles at C and E. CEDF is a square and the length of DE is 59.5 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 59.5
= 119 cm
Perimeter of the unshaded part
=
12 x 3.14 x 119
= 186.83 cm
(b)
Area of the unshaded part
= Area of the semicircle - Area of the triangle
=
12 x 3.14 x 59.5 x 59.5 -
12 x 119 x 59.5
= 5558.1925 - 3540.25
= 2017.9425 cm
2 Area of the circle
= 3.14 x 59.5 x 59.5
= 11116.385 cm
2 Total area of the shaded parts
= 2 x (Area of the circle - Area of unshaded part)
= 2 x (11116.385 - 2017.9425)
= 2 x 9098.4425
= 18196.885 cm
2 Answer(s): (a) 186.83 cm; (b) 18196.885 cm
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