This is a tedious process but in the end is straightforward. Instead of imagining coordinate points, imagine a circle with a diameter going through it. How does one find the center of the circle? The midpoint of the diameter, right?
Coming back into coordinate points, we know we have to use the midpoint formula:
[ (x1 + x2)/2 , (y1 + y2)/2 ]
Plug in the coordinate points: x1 = -3 x2 = -11 y1 = -5 y2 = -7
