The reflection (flip) of a figure is drawn over a given line.
After completing this tutorial, you will be able to complete the following:
Transformations that create images that are congruent to the original figure are called rigid transformations.
The word isometries, meaning rigid transformations, comes from the Greek phrases isometry, meaning equal measure. There are three basic isometries: translations, reflections, and rotations.
All three of these are considered isometric because they preserve congruence. In other words, a transformation in which the original figure and transformed figure have the same side lengths and angle measurements is considered to be isometric.
The mirror image produced by flipping a figure over a line is called reflection.
A reflection is a flip. The figure is simply flipped over a line (called line of reflection), either horizontally or vertically, from its original space maintaining the figure's congruence. In other words, the shape and the size of the figure remain the same. However, the orientation and location change. The examples below show vertical and horizontal reflections over a line.
In both examples, the blue figure is the original figure. The red figure represents the flip, or reflection and it is called the image if the original figure. Notice that every point of the image under a reflection is the same distance from the line of reflection as the corresponding point on the original figure. Notice also that how the red figure is congruent -same shape and same size, as the original figure. However, the orientation and the location of the red figure changed.
|Approximate Time||20 Minutes|
|Pre-requisite Concepts||Students should know the definitions of reflection and symmetry.|
|Type of Tutorial||Skills Application|
|Key Vocabulary||flip, line, orientation|