PSLE The figure is made up of 6 identical quadrants and 2 identical semicircles. The radius of each quadrant is 11 cm. The unshaded area marked A is enclosed by 2 quadrants and 2 semicircles. (Take π = 3.14)
- Find the perimeter of F.
- Find the total shaded areas.
(a)
Perimeter of 2 semicircles
= 3.14 x 11
= 34.54 cm
Diameter of the quadrant
= 2 x 11
= 22 cm
Perimeter of 2 quadrants
=
12 x 3.14 x 22
= 34.54 cm
Perimeter of F
= 34.54 + 34.54
= 69.08 cm
(b)
Area of the large circle
= 3.14 x 11 x 11
= 379.94 cm
2 Area of 2 semicircles
= 3.14 x 5.5 x 5.5
= 94.985 cm
2 Area of 2 boomerangs
= Area of the rectangle - Area of the semicircle
= 22 x 11 -
12 x 3.14 x 11 x 11
= 242 - 189.97
= 52.03 cm
2 Total shaded areas
= 379.94 - 94.985 - 52.03
= 232.925 cm
2 Answer(s): (a) 69.08 cm; (b) 232.925 cm
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