\circle ¶Synopsis:
\circle{diameter}
\circle*{diameter}
Produces a circle with a diameter as close as possible to the specified
one. The * form produces a filled-in circle.
This draws a circle of radius 6, centered at (5,7).
\put(5,7){\circle{6}}
The available radii for \circle are, in points, the even
numbers from 2 to 20, inclusive. For \circle* they are all the
integers from 1 to 15.