Mirror Reflection

the transformation of a space with respect to a given plane a for which to a point P located to one side of the plane a there corresponds a point P’ located on the other side of a in such a way that the plane a is perpendicular to the segment PP’ and passes through its center. A mirror reflection leaves the points in plane a unchanged. The mirror reflection of a plane with respect to a given straight line is defined analogously.

Figure 1