The area of a square is given by the equation [tex]A= s^{2} [/tex]
The area of a circle is given by the equation [tex]A=\pi r^{2}[/tex]
Set these two equations equal to one another because the areas are equal, and then rearrange the equation in terms of r:
[tex]s^{2}=\pi r^{2}[/tex]
[tex]s= \sqrt{\pi r^{2} } [/tex]