Final answer:
The special marks used to show that segments are congruent are marks of hash.
Step-by-step explanation:
The special marks used to show that segments are congruent are marks of hash. These marks are typically two short parallel lines drawn across the segments or a series of equal-sized dashes on top of the segments. For example, if segment AB is congruent to segment CD, these marks would be placed on segment AB and segment CD to indicate their congruence.
Learn more about congruent segments