ARC allows you to create an arc entity.

Create an arc entity by choosing from the following 
options:

CTR+RAD - to create an arc by specifying start and end
angles, a center position, and a radius.

CTR+DIA - to create an arc by specifying start and end
angles, a center position, and a diameter.

CTR+EDG - to create an arc by specifying start and end
angles, a center position, and an edge point.

THREE-P - to create an arc by indicating three points on
its circumference.

TANGENT - to create an arc either: tangent to one entity,
with its center at an indicated position; tangent to two
entities, with a specified radius; or tangent to three
entities.

BEG+END - to create an arc by specifying the start point,
endpoint, and the included angle.

ROUND - to create an arc that is tangent to the endpoint 
of a curve (excluding circles).
