PSLE The figure is made up of 6 identical quadrants and 2 identical semicircles. The radius of each quadrant is 17 cm. The unshaded area marked A is enclosed by 2 quadrants and 2 semicircles. (Take π = 3.14)
- Find the perimeter of Q.
- Find the total shaded areas.
(a)
Perimeter of 2 semicircles
= 3.14 x 17
= 53.38 cm
Diameter of the quadrant
= 2 x 17
= 34 cm
Perimeter of 2 quadrants
=
12 x 3.14 x 34
= 53.38 cm
Perimeter of Q
= 53.38 + 53.38
= 106.76 cm
(b)
Area of the large circle
= 3.14 x 17 x 17
= 907.46 cm
2 Area of 2 semicircles
= 3.14 x 8.5 x 8.5
= 226.865 cm
2 Area of 2 boomerangs
= Area of the rectangle - Area of the semicircle
= 34 x 17 -
12 x 3.14 x 17 x 17
= 578 - 453.73
= 124.27 cm
2 Total shaded areas
= 907.46 - 226.865 - 124.27
= 556.325 cm
2 Answer(s): (a) 106.76 cm; (b) 556.325 cm
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