To Extend or Shorten Overlapping Element to Its Intersection with Another Element

In the AccuSnap Settings dialog, turn off the Identify Elements Automatically check box.
Select the Trim to Element tool ( Drawing > Home > Modify ).
In the tool settings window, turn on the Select cutting element first check box.
Select the segment of the cutting element.
Select the segment of the element to be extended or shortened.
Click reset.
The entire element is selected.
Click reset.
The segment of overlapping element is selected.
Click reset.
The entire overlapping element is selected.
Enter a data point to extend or shorten the element.
The overlapping element is extended or shortened to the intersection with the segment of the cutting element.

Left: The first element is extended to the intersection with the segment of the cutting element. Right: The overlapping element is extended to the intersection with the segment of the cutting element.