Finding the point where the angle of incidence is equal to the angle of reflection Say I have two points, $$A=(-1,1)\\B=(2,1)$$ and a line at $$y=0$$ How do I find the point on the line that makes A and B have the same angle?


In order to have the same angle it is enough to have 
$$PD=PC=\frac{3}{2}\to 2-x=\frac{3}{2}\to x=\frac{1}{2}$$
