PSLE In Figure 1, VWXY is a rectangular piece of paper. After 4 identical triangles are cut out from the paper, the remaining paper is shown in Figure 2. The area of the remaining paper is 240 cm
2.
- What is the area of each triangle that was cut out?
- The perimeter of Figure 2 is 44 cm longer than the perimeter of Figure 1. What is the perimeter of each triangle?
(a)
Area of Rectangle VWXY
= 28 x 10
= 280 cm
2 Area of the 4 triangles
= 280 - 240
= 40 cm
2 Area of each triangle that was cut out
= 40 ÷ 4
= 10 cm
2 (b)
Perimeter of Rectangle VWXY
= 2(28 + 10)
= 2 x 38
= 76 cm
Perimeter of Figure 2
= 76 + 44
= 120 cm
Sum of the lengths of all the jagged edges
= 120 - (2 x 28)
= 120 - 56
= 64 cm
Sum of the lengths of the jagged edges of 1 triangle
= 64 ÷ 4
= 16 cm
Base of each triangle
= 10 ÷ 2
= 5 cm
Perimeter of each triangle
= 16 + 5
= 21 cm
Answer(s): (a) 10 cm
2; (b) 21 cm