Creating Arcs by Center, Radius, and Arc angle

Is there a way to create (script)  an arc by center, radius and arc angle?  or by 3 points?

By arc i mean a regular arc, as in a piece of a circle.  It seems the native illustrator tools make it very difficult to create a regular arc in the normal CAD way of drawing one.  I found a forum post from a guy years ago that said he had created script to make arcs this way.  Have you come across this anywhere? Any ideas?

Thanks,