PSLE Figure 1 shows a trapezium which has a perimeter of 83 cm. Kathy joins three such trapeziums to form Figure 2 which has a perimeter of 169 cm.
- Find the length of AB.
- Kathy joins another four such trapeziums to form Figure 3 which has an area of 1640 cm2. Find the length of XY.
(a)
Perimeter of three separate trapeziums
= 3 x 83
= 249 cm
Number of overlapping ABs = 4
Length of 4 ABs
= 249 - 169
= 80 cm
Length of 1 AB
= 80 ÷ 4
= 20 cm
(b)
Area of 2 rectangles
= 1640 ÷ 2
= 820 cm
2 Length of the rectangle
= 820 ÷ 20
= 41 cm
Length of XY
= 41 - 20 - 9
= 12 cm
Answer(s): (a) 20 cm; (b) 12 cm