Perimeter of a shape is the total length of its border
Figure 1, perimeter = 5 units
Figure 2, perimeter = 7 units
Figure 3, perimeter = 9 units
Figure 4, perimeter = 11 units
Notice that the perimeter is forming an Arithmetic sequence; 5, 7, 9, 11 with a common difference of 2
The general form of an Arithmetic sequence is
[tex]n_{th}term=dn+0^{th}term[/tex]
Where 'd' is a common difference and 'n' is the number of terms.
We have d = 2, and
zero term = the term before the first term = 3
[tex]n_{th}term=2n+3[/tex] ⇒ This is the rule to find the perimeter of the next figures
