Squares of sides 5 cm are arranged to create a pattern as shown.
- Find the number of squares needed for Figure 29.
- Find the area of Figure 15.
- Find the perimeter of Figure 27.
(a)
Pattern for the number of squares
Pattern 1: 1
Pattern 2: 1 + 2 = 3
Pattern 3: 1 + 2 + 3 = 6
Pattern 4: 1 + 2 + 3 + 4 = 10
Formula:
Number of squares = Pattern number x (Pattern number +1) ÷ 2
Number of squares for Pattern 29
= 29 x (29 + 1) ÷ 2
= (29 x 30) ÷ 2
= 435
(b)
Number of squares for Pattern 15
= 15 x (15 + 1) ÷ 2
= 15 x 16 ÷ 2
= 240 ÷ 2
= 120
Area of a square = 5 x 5 = 25 cm
2 Area of Pattern 15
= 120 x 25
= 3000 cm
2 (c)
Pattern for the perimeter in cm
Pattern 1: 1 x (4 x 5) = 20
Pattern 2: 2 x (4 x 5) = 40
Pattern 3: 3 x (4 x 5) = 150
Pattern 4: 4 x (4 x 5) = 80
Formula:
Perimeter of the pattern = Pattern number x (4 x side length)
Perimeter of Pattern 27
= 27 x (4 x 5)
= 27 x 20
= 540 cm
Answer(s): (a) 435; (b) 3000 cm
2; (c) 540 cm