PSLE In Figure 1, KLMN 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 624 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 KLMN
= 32 x 24
= 768 cm
2 Area of the 8 triangles
= 768 - 624
= 144 cm
2 Area of each triangle that was cut out
= 144 ÷ 8
= 18 cm
2 (b)
Perimeter of Rectangle KLMN
= 2(32 + 24)
= 2 x 56
= 112 cm
Perimeter of Figure 2
= 112 + 80
= 192 cm
Sum of the lengths of all the jagged edges
= 192 - (2 x 32)
= 192 - 64
= 128 cm
Sum of the lengths of the jagged edges of 1 triangle
= 128 ÷ 8
= 16 cm
Base of each triangle
= 24 ÷ 4
= 6 cm
Perimeter of each triangle
= 16 + 6
= 22 cm
Answer(s): (a) 18 cm
2; (b) 22 cm