How To: Move a polygon vertex along the bearing from its originating segment
When moving a vertex that is part of a line or polygon, it is not possible to specify a bearing or direction to constrain the movement. The instructions provided describe how to move a vertex from a polygon along the bearing from its originating segment.
In ArcMap, create a line feature class using the Create Feature Class tool.
Draw a temporary line along the polygon segment with the desired bearing.
Click the Create Feature button on the Editor toolbar to open the Create Features window.
Ensure the Snapping function is enabled and Edge Snapping is selected.
Create a line starting from one vertex on the desired polygon segment.
Drag the line across the polygon segment, staying snapped to the edge, and press Ctrl+P (parallel).
Ctrl+P constrains the digitized line to segment's bearing.
Extend the line to the desired length and finish the sketch.
Start an edit session on the polygon layer, and select the polygon feature using the Edit tool .
Right-click the polygon feature > Edit Vertices to expose the polygon vertices.
Move the polygon vertex and snap to the extended line.
Save the edits, and stop the edit session.
Remove the temporary line.
The vertex is moved along the same bearing as its originating segment.