CTR+RAD allows you to create a circle by specifying a
center position and a radius.

Enter a value for the radius and press <Enter>, or accept
the default value displayed in parentheses by pressing
<Enter>.

Indicate the center point of the circle, using an option
from the Position Menu.

In 2-D construction mode, the center point is projected to
the current construction plane, and the circle is created
in the current construction plane.

In 3-D construction mode, the circle is created in the 
plane that is parallel to the current construction plane 
and passes through the center point.
