TRIM allows you to create an arc fillet and trim the 
tangent entities at their intersections with the 
fillet.

Enter a value for the radius of the arc fillet and press
<Enter>, or accept the default value by pressing <Enter>.

Select the first entity, near the tangency point on the
portion you want remaining after the entity is trimmed.

If necessary, you can cancel the first selection by 
choosing the BACK-UP option and selecting a different
entity.

Select the second entity, near the tangency point on 
the portion you want remaining after the entity is
trimmed.

If the specified radius is greater than half the maximum
distance between the selected entities, an error message 
is displayed. If this occurs, press <Enter> to clear the
message, choose the BACK-UP option, enter a different 
radius value, and reselect the entities.

In 2-D construction mode, the selected entities are
projected to the current construction view, at the current
depth. The arc fillet is created in the current 
construction view, at the depth that is active when the 
second entity is selected. 

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