For a square: [tex]A=s^{2}[/tex]
Solve for the length of a side by taking the square root of both sides:
[tex]\sqrt{A}=\sqrt{s^{2}}[/tex]
[tex]\sqrt{A}=s[/tex]
Now we can substitute known values:
[tex]s=\sqrt{A}[/tex]
[tex]s=\sqrt{441ft^{2}}[/tex]
[tex]s=21ft[/tex]
