PSLE Figure 1 shows a trapezium which has a perimeter of 89 cm. Risa joins three such trapeziums to form Figure 2 which has a perimeter of 187 cm.
- Find the length of AB.
- Risa joins another four such trapeziums to form Figure 3 which has an area of 1840 cm2. Find the length of XY.
(a)
Perimeter of three separate trapeziums
= 3 x 89
= 267 cm
Number of overlapping ABs = 4
Length of 4 ABs
= 267 - 187
= 80 cm
Length of 1 AB
= 80 ÷ 4
= 20 cm
(b)
Area of 2 rectangles
= 1840 ÷ 2
= 920 cm
2 Length of the rectangle
= 920 ÷ 20
= 46 cm
Length of XY
= 46 - 20 - 12
= 14 cm
Answer(s): (a) 20 cm; (b) 14 cm