Answer :
[tex]\Delta\ EFG\ is\ right\ triangle\ :)\ (look\ at\ the\ picture)\\\\Circumference\ of\ right\ triangle\ is\ in\ the\ middle\ of\ the\ hypotenuse\ (EG).\\\\C\left(\frac{3+7}{2};\ \frac{6+4}{2}\right)\to\boxed{C(5;\ 5)}[/tex]