3 ENTS allows you to create an arc tangent to three 
selected entities.

Enter a value (in degrees) for the start angle and press
<Enter>, or accept the default value in parentheses by 
pressing <Enter>.

Enter a value (in degrees) for the end angle and press
<Enter>, or accept the default value in parentheses by 
pressing <Enter>.

Select the first tangent entity, near the point of
tangency. If necessary, you can cancel the selection
by choosing the BACK-UP option and selecting another 
entity.

Select the second entity.

Select the third tangent entity, near the point of 
tangency.

An error message is displayed if a tangent arc cannot 
be created; for example, because the selected entities 
are not coplanar and you are in 3-D construction mode. 
You are prompted to press <Enter> and to select a 
different entity as the first tangent entity.

In 2-D construction mode, the arc is created in the 
construction view, at the depth that is active when the
third tangent entity is selected.

In 3-D construction mode, the arc is created in the plane
of the selected entities.
