Define a Ring of Circles ROC(n,r,P,a) as a set of
n≥3 circles (each with radius r, each with center on
a circle with center P and radius a, and each
externally tangent to both its neighbors).

With b>a, each of the circles in ROC(6,R,P,b)
is externally tangent to two of the circles in
ROC(6,r,P,a).

What is the ratio b/a?

Extra credit - what is the ratio if 6
is replaced with n in the problem?