Reflections
The above figure is an example of a reflection about the x-axis. Reflections are rigid motions that reflect, or "flip", a pre-image across a line called the line of reflection. Reflections are written as r(line of reflection). The example above is denoted as rx-axis. Each point on the pre-image and its corresponding point on the image are equidistant from the line of reflection. When reflecting a shape, all line segments and angle measures are preserved.