All you have to do is use the midpoint formula.......because the center of a circle lies in the center of a diameter.
Now,
We know,
\($Midpoint formula = ($\frac{x_1+x_2}{2} , \frac{y_1+y_2}{2}) \\\\ $Midpoint formula = ($\frac{(-3)+(-11)}{2} , \frac{(-5)+(-7)}{2} ) \\\\ $Midpoint formula = ($\frac{-14}{2} , \frac{-12}{2}) \\\\ $Midpoint = (-7,-6)\)
So,
The center of the circle is (-7 , -6)
