Parallel line are created in much the same as tangent line. select application or modelling.
create line.
Open the Line tool.
Make sure the Associative option is selected.
Select a start point for the new line. Use the Snap Point tool to aid object selection.
The New Line Start Point with Inferred Auto-Plane
For clarity in this example, we have used F3 to turn off most of the dynamic input boxes.
Set the end constraint to Angle.
Select the existing line you want the new line to be parallel with.
Existing Line Highlighted
The Angle Handle Displays on Selection of the Line
The auto-plane changes to match the plane of the selected line, and the Angle handle and a dashed reference line displays.
If Snap Point is disabled, you can select the existing line without having to first set the end constraint to Angle, as the system will infer the Angle constraint anyway.
Drag the angle handle to 180 or 0 degrees. The parallel symbol displays when the line is parallel.
At 0 or 180 Degrees the Lines are Parallel
As you drag the angle handle, a parallel symbol displays at 0 and 180 degrees in reference to the selected line, and a perpendicular symbol at 90 and 270 degrees.
Drag the start and/or end handles or specify a value to get the desired length.
Click MB2 or Apply to create the parallel line.
