Answer: [tex]3\sqrt{2}\ m[/tex]
Step-by-step explanation:
The perimeter of a square is:
[tex]P=4s[/tex]
Where "s" is the lenght of a side of the square.
Then, if the perimeter of this square is 12 m, you can solve for "s" and find its value:
[tex]s=\frac{P}{4}\\\\s=\frac{12\ m}{4}\\\\s=3\ m[/tex]
You can calculate the length of the diagonal with this formual:
[tex]d=s\sqrt{2}[/tex]
Where "s" is the lenght of a side of the square.
Substituting the value of "s" into the formula [tex]d=s\sqrt{2}[/tex], you get that the lenght of the diagonal of this square is:
[tex]d=3\sqrt{2}\ m[/tex]