PSLE In Figure 1, WXYZ is a rectangular piece of paper. After 8 identical triangles are cut out from the paper, the remaining paper is shown in Figure 2. The area of the remaining paper is 320 cm
2.
- What is the area of each triangle that was cut out?
- The perimeter of Figure 2 is 80 cm longer than the perimeter of Figure 1. What is the perimeter of each triangle?
(a)
Area of Rectangle WXYZ
= 25 x 16
= 400 cm
2 Area of the 8 triangles
= 400 - 320
= 80 cm
2 Area of each triangle that was cut out
= 80 ÷ 8
= 10 cm
2 (b)
Perimeter of Rectangle WXYZ
= 2(25 + 16)
= 2 x 41
= 82 cm
Perimeter of Figure 2
= 82 + 80
= 162 cm
Sum of the lengths of all the jagged edges
= 162 - (2 x 25)
= 162 - 50
= 112 cm
Sum of the lengths of the jagged edges of 1 triangle
= 112 ÷ 8
= 14 cm
Base of each triangle
= 16 ÷ 4
= 4 cm
Perimeter of each triangle
= 14 + 4
= 18 cm
Answer(s): (a) 10 cm
2; (b) 18 cm