The figure is made up of a right-angled triangle HKL and two semicircles with HK and KL as their diameters respectively. The two semicircles and the line HL meet at N as shown. HK = 18 cm. KL = 24 cm and HL = 30 cm. (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 HNK
=
12 x 3.14 x 18
= 28.26 cm
Circumference of Semicircle LNK
=
12 x 3.14 x 24
= 37.68 cm
Perimeter of shaded region
= Circumference of semicircles + HL
= 28.26 cm + 37.68 cm + 30 cm
= 95.94 cm
(b)
Area of Triangle HKL
=
12 x 24 x 18
= 216 cm
2 Area of Semicircle HNK
=
12 x 3.14 x 9 x 9
= 127.17 cm
2 Area of Semicircle LNK
=
12 x 3.14 x 12 x 12
= 226.08 cm
2 Area of the shaded region
= 127.17 + 226.08 - 216
= 137.25 cm
2 Answer(s): (a) 95.94 cm; (b) 137.25 cm
2