PSLE Figure 1 shows a trapezium which has a perimeter of 78 cm. Diana joins three such trapeziums to form Figure 2 which has a perimeter of 162 cm.
- Find the length of AB.
- Diana joins another four such trapeziums to form Figure 3 which has an area of 1368 cm2. Find the length of XY.
(a)
Perimeter of three separate trapeziums
= 3 x 78
= 234 cm
Number of overlapping ABs = 4
Length of 4 ABs
= 234 - 162
= 72 cm
Length of 1 AB
= 72 ÷ 4
= 18 cm
(b)
Area of 2 rectangles
= 1368 ÷ 2
= 684 cm
2 Length of the rectangle
= 684 ÷ 18
= 38 cm
Length of XY
= 38 - 18 - 9
= 11 cm
Answer(s): (a) 18 cm; (b) 11 cm