Final answer:
In a reflection transformation, the congruence of a shape is preserved, meaning its size and shape do not change, but its orientation is inverted across the line of reflection.
Step-by-step explanation:
When a shape undergoes a reflection transformation, its congruence is preserved, meaning that the size and shape remain unchanged. However, the orientation of the shape is altered. Specifically, a reflection across a line, like an image seen in a plane mirror, retains the object's size and shape, but flips the shape over the line of reflection. This flipping changes the orientation in a manner similar to reversing left and right. For curved mirrors, using ray tracing and geometric formulas, we can deduce similar effects on image formation by reflection. An example is the use of plane mirrors where an image maintains the same height and orientation as the object, appearing upright and at the same distance behind the mirror but with left and right inverted as if the front and back were switched.