The figure is made up of a right-angled triangle GHK and two semicircles with GH and HK as their diameters respectively. The two semicircles and the line GK meet at L as shown. GH = 18 m. HK = 24 m and GK = 30 m. (Take π = 3.14)
- Find the perimeter of the shaded region. Correct the answer to 2 decimal places.
- Find the area of the shaded region.
(a)
Circumference of Semicircle GLH
=
12 x 3.14 x 18
= 28.26 m
Circumference of Semicircle KLH
=
12 x 3.14 x 24
= 37.68 m
Perimeter of shaded region
= Circumference of semicircles + GK
= 28.26 m + 37.68 m + 30 m
= 95.94 m
(b)
Area of Triangle GHK
=
12 x 24 x 18
= 216 m
2 Area of Semicircle GLH
=
12 x 3.14 x 9 x 9
= 127.17 m
2 Area of Semicircle KLH
=
12 x 3.14 x 12 x 12
= 226.08 m
2 Area of the shaded region
= 127.17 + 226.08 - 216
= 137.25 m
2 Answer(s): (a) 95.94 m; (b) 137.25 m
2