Each of the figure is made up of 5-cm sticks. The table shows the total length of sticks used for each figure and the perimeter of each figure.
- Complete the table for Figure 4 (i).
- Complete the table for Figure 4 (ii).
- Which figure number will have a perimeter of 690 cm?
(a)
Pattern of the total length of sticks
Figure 1: (1 x 11 + 1) x 5 = 60 cm
Figure 2: (2 x 11 + 1) x 5 = 115 cm
Figure 3: (3 x 11 + 1) x 5 = 170 cm
Formula:
Total length of sticks = (Figure number x 11 + 1) x 5
Total length of sticks for Figure 4
= (4 x 11 + 1) x 5
= 45 x 5
= 225 cm
(b)
Pattern of the perimeter
Figure 1: (1 x 4 + 2) x 5 = 30 cm
Figure 2: (2 x 4 + 2) x 5 = 50 cm
Figure 3: (3 x 4 + 2) x 5 = 70 cm
Formula:
Perimeter of Figure= (Figure number x 4 + 2) x 5
Perimeter of Figure 4
= (4 x 4 + 2) x 5
= 18 x 5
= 90 cm
(c)
(Figure number x 4 + 2) x 5 = 690
Figure number x 4 + 2 = 690 ÷ 5
Figure number x 4 + 2 = 138
Figure number x 4 = 138 - 2
Figure number x 4 = 136
Figure number = 136 ÷ 4
Figure number = 34
Answer(s): (a) 225; (b) 90; (c) 34