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

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

Enter the end angle in the same manner. Indicate a center
position for the arc, using a Position Menu option.

Indicate the edge position of the arc in the same manner.

In 2-D construction mode, the center and edge points are
projected to the current construction plane, and the arc 
is created in the current construction plane.

In 3-D construction mode, the system locates a plane that 
is parallel to the current construction plane and passes
through the center point. The edge point is projected to
this plane and the arc is created in this plane.
