Answer: The required length of segment A'B' is 2 units.
Step-by-step explanation: Given that the triangle ABC is reflected to form triangle A'B'C'.
We are to find the length of segment A'B'.
From the graph, we note that
the co-ordinates of the vertices A and B are (3, -2) and (3, 0) respectively.
So, using distance formula, the length of the segment AB is given by

Since reflection of a figure does not change its shape and size, so the length of segment A'B' is equal to the segment AB.
Thus, the required length of segment A'B' is 2 units.