tangential connectors
 

I'm trying to draw a 'blow up' of a part of a drawing by putting a circle around the area in the original drawing, with a larger circle showing the detail off to the side. I'd like to draw a couple of connectors that are tangential to the two circles (and stop on the edge of each). Is there an easy way to do this or do I have to add magnets to each and then manually move them if I move the circles relative to each other?

tia
Tim