In order to find this, we need to first determine what to use as the base of the triangle. Since when we draw it, the line between G and H is a flat line, it is the easiest to use as a base. Finding the length of the base is easy because we are simply looking for the difference in the x values.
6 - -2 = 8 = base
Now that we have the base, we need to find the height. The height is always the perpendicular line from the 3rd point to the base line. In this case, this would just be the change in y from the other two.
5 - -1 = 6 = height
Now that we have those two distances, we can just use the triangle formula.
