Reflection - GCSE Maths Definition

In GCSE Mathematics, a reflection is a transformation reflects (reverses the orientation of; "flips") a shape (called the object) in a line (called the line of reflection or mirror line) to create an image. As with all transformations, it is easier to consider the vertices of the shape being reflected, then (re)connected accordingly. Lines of reflection may be horizontal (of the form y = k), vertical (of the form x = k) or oblique (diagonal, of the form y = mx + c).

Reflection is related to symmetry, but be careful on how this is described. A line of symmetry "cuts a shape in half" but a reflection would transform the whole shape. For shapes that appear on both sides of the line of reflection, there would be a two-way reflection - in such cases any points on the line of reflection will stay in the same place (a bit like touching a mirror, the point of contact with the mirror would not get reflected).