Final answer:
To find the length of segment a'a, we use geometric properties of parallel lines and shapes formed. The method varies based on the additional information provided.
Step-by-step explanation:
The length of segment a'a can be derived from the properties of parallel lines and the geometric figures involved. Assuming we are dealing with a geometry problem where line segments a'b' and ab are parallel, we often use properties of similar triangles or parallelograms to find missing lengths. Depending on the additional information provided, such as angles or other lengths, the exact method to calculate the length of segment a'a could vary. Typically, this could involve using the Pythagorean theorem, trigonometry, or the properties of similar shapes.