If there are two circles with known position and radius, and one (the smaller one) is inside the other, how do I find the distance between their edges?
How would I find the length of the drawn line?
Note that if the circles had the same center (concentric) , the value would be R1- R2
But R2 is moved a distance equal to the distance between C2 and C1 this reduces R1-R2 by this amount
So the line will be (R1-R2) - distance betweenC2 and C1 (sorry...that black R1 should be labelled R2)