Reflection

The reflection of point \(M\) over line \(\Line{l}\) is the point \(M'\) such that line \(\Line{l}\) is perpendicular bisector to the segment \(\Segment{MM'}\).

The reflection of an object over line \(\Line{l}\) flips all its points, creating a mirror image of the object.

Imagine folding a piece of paper along the axis; the shape on one side of the fold matches its reflection on the other side.

A line is an axis of symmetry when the reflection of an object over this line matches the object.