Each of the figure is made up of 3-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 7 (i).
- Complete the table for Figure 7 (ii).
- Which figure number will have a perimeter of 450 cm?
(a)
Pattern of the total length of sticks
Figure 1: (1 x 11 + 1) x 3 = 36 cm
Figure 2: (2 x 11 + 1) x 3 = 69 cm
Figure 3: (3 x 11 + 1) x 3 = 102 cm
Formula:
Total length of sticks = (Figure number x 11 + 1) x 3
Total length of sticks for Figure 7
= (7 x 11 + 1) x 3
= 78 x 3
= 234 cm
(b)
Pattern of the perimeter
Figure 1: (1 x 4 + 2) x 3 = 18 cm
Figure 2: (2 x 4 + 2) x 3 = 30 cm
Figure 3: (3 x 4 + 2) x 3 = 42 cm
Formula:
Perimeter of Figure= (Figure number x 4 + 2) x 3
Perimeter of Figure 7
= (7 x 4 + 2) x 3
= 30 x 3
= 90 cm
(c)
(Figure number x 4 + 2) x 3 = 450
Figure number x 4 + 2 = 450 ÷ 3
Figure number x 4 + 2 = 150
Figure number x 4 = 150 - 2
Figure number x 4 = 148
Figure number = 148 ÷ 4
Figure number = 37
Answer(s): (a) 234; (b) 90; (c) 37