12.5. Reflections http://www.ck12.org
Vocabulary
Atransformationis an operation that moves, flips, or otherwise changes a figure to create a new figure. Arigid
transformation(also known as anisometryorcongruence transformation) is a transformation that does not change
the size or shape of a figure. The new figure created by a transformation is called theimage. The original figure is
called thepreimage. Areflectionis a transformation that turns a figure into its mirror image by flipping it over a
line. Theline of reflectionis the line that a figure is reflected over.
Guided Practice
- Reflect the line segmentPQwith endpointsP(− 1 , 5 )andQ( 7 , 8 )over the liney=5.
- A triangle 4 LMNand its reflection, 4 L′M′N′are to the left. What is the line of reflection?
- Reflect the trapezoidTRAPover the liney=−x.