Parallel

Creates a line parallel to a existing line.

Select an existing line.
Select the location of the parallel line, or enter the offset in the Inspector Bar. By default, the parallel line will have the same length as the original line.

Local menu option:

Keep Length (default): If not used, you can create a parallel line with a different length than the original line. You can only adjust one endpoint of the line - the endpoint closest to where you selected the original line. You can enter both the offset and length in the Inspector Bar.