we know that
Area of a circle is equal to
[tex]A=pi* r^{2} [/tex]
where
[tex]r[/tex] is the radius
in this problem we have that
[tex]A=50 m^{2} [/tex]
[tex]A=pi* r^{2} \\ r= \sqrt{A/pi} \\ r= \sqrt{50/pi} [/tex]
[tex]r=4 m [/tex]
we know that
the diameter is two times the radius
so
[tex]D=2r \\ D=2*4 \\ D=8 m [/tex]
