Sides of Triangles Obtained
ABO a/b + a a +1 a/b +1
BCO a + b a + 1 b + 1
CDO b + b/a b + 1 b/a + 1
DEO b/a + 1/a b/a + 1 1/a + 1
EFA 1/a +1/b 1 + 1/b 1 + 1/a
FAO a/b + 1/b a/b + 1 1/b + 1


I observe that triangles BCO, DEO and FAO are similar, with the similarity ratios (taking them two by two), 1: 1/a: 1/b respectively. So are triangles ABO, CDO and EFA, with the similarity ratios a: b: 1.

Looking in the similarity ratio, I observe that angle BOC is congruent with angle DEO and with angle AFO, angle OBC with angles FAO and EOD, and angle BCO with ODE and AOF.

This means the sum of angles BOC, AOF and DOE is the angle sum in a triangle, i.e. 1800.

For triangles AOB, COD and EOF that are similar, angles AOB, ODC and OEF are congruent; so are angles OAB, OFE and DOC and ABO, OCD and FOE. In this case the sum of angles: AOB, COD and EOF is 1800.

So, the sum of all angles around point O is 3600. This means that, with the given radii, it is always possible to construct such a flower.