TANGENT allows you to create an arc tangent to one, two,
or three entities.

Create a tangent arc by choosing from the following 
options:

CTR-ENT - to create an arc tangent to a selected entity 
with its center at an indicated position.

2 ENTS - to create an arc tangent to two selected entities
with a specified radius.

3 ENTS - to create an arc tangent to three selected
entities.

You cannot select 2-D entities (i.e., an arc, conic, or 
2-D spline) that appear as a straight line in the current
view.

In 3-D construction mode, the selected entities must be
coplanar. Polylines, polygons, and 3-D splines cannot
be selected in 3-D construction mode because they are
not planar entities.
