PSLEThe figure is made up of two rectangles, DELJ and JKGH, and two right-angled isosceles triangles, EFL and GFK. ED = 11 cm, GH = 7 cm and EL =
m cm. DJH and FLKJ are straight lines.
- Find the length of DH in terms of m. Give your answer in the simplest form.
- Find the total area of the figure when m = 12.
(a)
Length LK
= 11 - 7
= 4 cm
Length FL =
m cm (Isosceles triangle)
Length KG
= Length CG
= (
m + 4) cm (Isosceles triangle)
Length DH
=
m +
m + 4
= (2
m + 4) cm
(b)
Area of Rectangle DEJL
= 12 x 11
= 132 cm
2 Length JH
=
m + 4
= 12 + 4
= 16 cm
Area of Rectangle GHJK
= 16 x 7
= 112 cm
2 Area of Triangle EFL
=
12 x 12 x 12
= 72 cm
2 Area of Triangle FGK
=
12 x 16 x 16
= 128 cm
2 Total area of the figure
= 132 + 112 + 72 + 128
= 444 cm
2 Answer(s): (a) (2
m + 4) cm; b) 444 cm
2