PSLE In Figure 1, MNPQ 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 350 cm
2.
- What is the area of each triangle that was cut out?
- The perimeter of Figure 2 is 28 cm longer than the perimeter of Figure 1. What is the perimeter of each triangle?
(a)
Area of Rectangle MNPQ
= 38 x 10
= 380 cm
2 Area of the 4 triangles
= 380 - 350
= 30 cm
2 Area of each triangle that was cut out
= 30 ÷ 4
= 7.5 cm
2 (b)
Perimeter of Rectangle MNPQ
= 2(38 + 10)
= 2 x 48
= 96 cm
Perimeter of Figure 2
= 96 + 28
= 124 cm
Sum of the lengths of all the jagged edges
= 124 - (2 x 38)
= 124 - 76
= 48 cm
Sum of the lengths of the jagged edges of 1 triangle
= 48 ÷ 4
= 12 cm
Base of each triangle
= 10 ÷ 2
= 5 cm
Perimeter of each triangle
= 12 + 5
= 17 cm
Answer(s): (a) 7.5 cm
2; (b) 17 cm