solutions of T^6 ...:
r: 3.54409035955192285362, r/4: 0.886022589887980713404; 4R: 5.47239575756503210290, R: 1.36809893939125802572
r: 3.96076865240664525605, r/4: 0.990192163101661314012; 4R: 7.76615101307386215734, R: 1.94153775326846553933