PSLE The figure is formed by two identical circles at J and L. JLKM is a square and the length of KL is 24.5 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 24.5
= 49 cm
Perimeter of the unshaded part
=
12 x 3.14 x 49
= 76.93 cm
(b)
Area of the unshaded part
= Area of the semicircle - Area of the triangle
=
12 x 3.14 x 24.5 x 24.5 -
12 x 49 x 24.5
= 942.3925 - 600.25
= 342.1425 cm
2 Area of the circle
= 3.14 x 24.5 x 24.5
= 1884.785 cm
2 Total area of the shaded parts
= 2 x (Area of the circle - Area of unshaded part)
= 2 x (1884.785 - 342.1425)
= 2 x 1542.6425
= 3085.285 cm
2 Answer(s): (a) 76.93 cm; (b) 3085.285 cm
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