Reflection

We have all seen our reflections in a mirror.

In mathematics, a reflection is another type of transformation.

The word reflection comes from the Latin re- which means back and flectere meaning to bend. Reflection comes from to bend back.

When you look in a mirror light is bent back or reflected into your eyes and you can see an image of your face. In mathematics when we talk about reflections, points are being bent back in lines of reflection.

Here is an example of a reflection using a single point.

We are going to reflect point A in the Y axis.

The result is point A′ (pronounced A dash).

A′ is a reflection of A

When a point is reflected, the original point is always the same perpendicular (at right angles) distance from the line of reflection as the reflected point.

Shapes can also be reflected. Here we reflect quadrilateral ABCD in the X axis. Every point in quadrilateral A′B′C′D′ is the same perpendicular distance from the X axis as the corresponding point in ABCD.