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Preimage
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 preimage is the original figure before a transformation is applied.
Key Points:
It's the starting shape in any transformation (like a translation, reflection, rotation, or dilation).
The result after the transformation is called the image.
Points in the preimage are often labeled with letters like A, B, C, and the corresponding points in the image are labeled A′, B′, C′ (with prime symbols).
Example:
If you reflect triangle ABC over the y-axis to get triangle A′B’C’, then ABC is the preimage.
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