PSLE The figure is formed by two identical circles at E and G. EGFH is a square and the length of FG is 63 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 63
= 126 cm
Perimeter of the unshaded part
=
12 x 3.14 x 126
= 197.82 cm
(b)
Area of the unshaded part
= Area of the semicircle - Area of the triangle
=
12 x 3.14 x 63 x 63 -
12 x 126 x 63
= 6231.33 - 3969
= 2262.33 cm
2 Area of the circle
= 3.14 x 63 x 63
= 12462.66 cm
2 Total area of the shaded parts
= 2 x (Area of the circle - Area of unshaded part)
= 2 x (12462.66 - 2262.33)
= 2 x 10200.33
= 20400.66 cm
2 Answer(s): (a) 197.82 cm; (b) 20400.66 cm
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