Line Length

Shrinks or extends a line or line segment from either endpoint. Double lines and multi lines can also be used. If you use this tool on a polyline or polygon, any adjacent segment will move to accommodate the new endpoint.

Select the line or line segment close to the endpoint you want to move.
Move the cursor to set the new length, or enter the length or delta in the Inspector Bar. Negative values can be used, thereby extending the line in the opposite direction.

If another segment meets the moved endpoint, it is changed as well.

Note: You can use Line Length on splines and Beziers, however the extension will be straight element of the curve, not curved continuations as they are with arcs. 3D Polylines, and splines can also be used, but the resulting geometry will be derived relative to the objects workplane.