The perimeter of a polygon is the distance around it.
In the case of a square, since all its sides are equal, the perimeter is given by:
![\begin{gathered} P=a+a+a+a \\ P=4a \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/k765t6b110z9yxr7ce7v0k5dvlhrqgcy4p.png)
where a is the length of each side. Therefore the perimeter is:
![P=4a](https://img.qammunity.org/2023/formulas/mathematics/high-school/wolyzj7hxr8k230dln4bm73i2jjmwfvbom.png)
Two quantities are directly proportional if as one amount increases, another amount increases at the same rate. With this in mind we conclude that the perimeter of a square is proportional to its side length.
If a=6 then the perimter is:
![\begin{gathered} P=4(6) \\ P=24 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/i4buzlgkc5xwj1bqh8s2w2fatwozlt13no.png)
Therefore if the length is 6 the perimeter is 24.