The formula of the area of a circle with radius r:
[tex]A_O=\pi r^2[/tex]
We have
[tex]A_O=22\ m^2[/tex]
Substitute:
[tex]\pi r^2=22\ \ \ |:\pi\\\\r^2=\dfrac{22}{\pi}\to r=\sqrt{\dfrac{22}{\pi}}\ m[/tex]
If you want an approximation, then:
[tex]\pi\approx\dfrac{22}{7}\to r=\sqrt{\dfrac{22}{\frac{22}{7}}}=\sqrt{22\cdot\dfrac{7}{22}}=\sqrt7\ m\approx2.65\ m[/tex]
