Create tangents from a coordinate to an existing arc, circle or ellipse
entity with this tool.
Usage
Choose the desired
line type in the options
toolbar.
Use the mouse to specify the location of the start point of the line or
enter a coordinate in the command line.
Click the entity to which you want to create the tangent. Usually, two
tangents are possible. When moving the mouse around, you can see a preview of
the tangent that will be created.