I have 2 lines Line A, and Line B that share from point. The 2 lines at first share the same path and are parallel, then they split into different paths. I would like to calculate that segment in which they are parallel. Picture below further explains visually. Red part is the wanted part.
Note that the red segment might be multiple connected segments that make up the red path of each Polyline. I doubt there is an interface in the arcobjects in which calculates this, which means I have to calculate it manually. I need some suggestions to get the best accurate result of the shared length.