If you haven't been watching the thread in "Working With...", the only way to draw a line tangent to two arcs or circles is by using the geometric constuction methods we learned when we were drafting on the board -- there is no way to do it using the tangent snap in AC. This would be a useful addition in future AC releases.
More to the point drawing and arc between 2 arcs to the tangents of each of those arcs does not work either. It cannot be that hard to do can it, I mean if you can do it using a drawing board...?