First find the equation of the line, Ill use the first one as an example:
(-5,10) , ( -9,2)
To work out the gradient:


So the gradient of the line is 2
The midpoint of the line is

The gradient of the inverted line is -0.5 as it is the negative reciprocal of the gradient of the first line.
Here, we work out the equation of the bisector.


