PSLE In Figure 1, RSTU is a rectangular piece of paper. After 6 identical triangles are cut out from the paper, the remaining paper is shown in Figure 2. The area of the remaining paper is 432 cm
2.
- What is the area of each triangle that was cut out?
- The perimeter of Figure 2 is 60 cm longer than the perimeter of Figure 1. What is the perimeter of each triangle?
(a)
Area of Rectangle RSTU
= 33 x 18
= 594 cm
2 Area of the 6 triangles
= 594 - 432
= 162 cm
2 Area of each triangle that was cut out
= 162 ÷ 6
= 27 cm
2 (b)
Perimeter of Rectangle RSTU
= 2(33 + 18)
= 2 x 51
= 102 cm
Perimeter of Figure 2
= 102 + 60
= 162 cm
Sum of the lengths of all the jagged edges
= 162 - (2 x 33)
= 162 - 66
= 96 cm
Sum of the lengths of the jagged edges of 1 triangle
= 96 ÷ 6
= 16 cm
Base of each triangle
= 18 ÷ 3
= 6 cm
Perimeter of each triangle
= 16 + 6
= 22 cm
Answer(s): (a) 27 cm
2; (b) 22 cm