PSLE In Figure 1, GHJK 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 600 cm
2.
- What is the area of each triangle that was cut out?
- The perimeter of Figure 2 is 112 cm longer than the perimeter of Figure 1. What is the perimeter of each triangle?
(a)
Area of Rectangle GHJK
= 32 x 24
= 768 cm
2 Area of the 8 triangles
= 768 - 600
= 168 cm
2 Area of each triangle that was cut out
= 168 ÷ 8
= 21 cm
2 (b)
Perimeter of Rectangle GHJK
= 2(32 + 24)
= 2 x 56
= 112 cm
Perimeter of Figure 2
= 112 + 112
= 224 cm
Sum of the lengths of all the jagged edges
= 224 - (2 x 32)
= 224 - 64
= 160 cm
Sum of the lengths of the jagged edges of 1 triangle
= 160 ÷ 8
= 20 cm
Base of each triangle
= 24 ÷ 4
= 6 cm
Perimeter of each triangle
= 20 + 6
= 26 cm
Answer(s): (a) 21 cm
2; (b) 26 cm