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Reflection (Geometry)
See It in Action
Two examples of the idea done right—and one common look-alike that is not right.
EXAMPLE
EXAMPLE
NON-EXAMPLE
Definition
A reflection is a transformation that flips a figure over a line, creating a mirror image of the original figure.
Key Points:
The line the figure is flipped over is called the line of reflection.
Each point and its image are the same distance from the line of reflection but on opposite sides.
Reflections are a type of congruence (rigid) transformation, so the image is congruent to the preimage.
Example:
Reflecting a triangle over the x-axis means flipping it across that axis, so the top becomes the bottom (and vice versa), but the shape and size stay the same.
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