PSLE The figure is formed by two identical circles at S and U. SUTV is a square and the length of TU is 17.5 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 17.5
= 35 cm
Perimeter of the unshaded part
=
12 x 3.14 x 35
= 54.95 cm
(b)
Area of the unshaded part
= Area of the semicircle - Area of the triangle
=
12 x 3.14 x 17.5 x 17.5 -
12 x 35 x 17.5
= 480.8125 - 306.25
= 174.5625 cm
2 Area of the circle
= 3.14 x 17.5 x 17.5
= 961.625 cm
2 Total area of the shaded parts
= 2 x (Area of the circle - Area of unshaded part)
= 2 x (961.625 - 174.5625)
= 2 x 787.0625
= 1574.125 cm
2 Answer(s): (a) 54.95 cm; (b) 1574.125 cm
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