PSLEThe figure is made up of two rectangles, JKRP and PQMN, and two right-angled isosceles triangles, KLR and MLQ. KJ = 8 cm, MN = 5 cm and KR =
s cm. JPN and LRQP are straight lines.
- Find the length of JN in terms of s. Give your answer in the simplest form.
- Find the total area of the figure when s = 18.
(a)
Length RQ
= 8 - 5
= 3 cm
Length LR =
s cm (Isosceles triangle)
Length QM
= Length CG
= (
s + 3) cm (Isosceles triangle)
Length JN
=
s +
s + 3
= (2
s + 3) cm
(b)
Area of Rectangle JKPR
= 18 x 8
= 144 cm
2 Length PN
=
s + 3
= 18 + 3
= 21 cm
Area of Rectangle MNPQ
= 21 x 5
= 105 cm
2 Area of Triangle KLR
=
12 x 18 x 18
= 162 cm
2 Area of Triangle LMQ
=
12 x 21 x 21
= 220.5 cm
2 Total area of the figure
= 144 + 105 + 162 + 220.5
= 631.5 cm
2 Answer(s): (a) (2
s + 3) cm; b) 631.5 cm
2