The new position of a point, a line, a line segment, or a figure after a transformation is called its image.
In the example shown below, triangle A'B'C is the image of triangle A'B'C, after translation.
Points A'B'C are the images of points A, B, and C respectively.
The line segments A'B', B'C', and A'C' are the images of the original line segments AB, BC, and AC respectively.

A. Similar
B. Congruent
C. Increase in size
D. None of the above
Correct Answer: B
Step 1: A reflection flips the figure across a line. The new figure is a mirror image of the original figure.
Step 2: So, the image of the polygon reflected over a line is congruent with respect to the original polygon.
Q1: What is the image of a polygon reflected over a line with respect to the original polygon?
Q: Is the image always the same size as the original?
A: Not always. Transformations like dilations change the size. Transformations like translations, rotations, and reflections do not change the size and maintain congruence.
Q: How do I find the image of a point after a transformation?
A: Apply the rules of the transformation to the coordinates of the point.