Packing $11$ unit circles in an equilateral triangle
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The side length of the smallest equilateral triangle into which $11$ unit circles can be packed.
Value: $4+2\sqrt{3}+\frac{4\sqrt{6}}{3}$ (≈10.73009)
Updates
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Upper bound: $4+2\sqrt{3}+\frac{4\sqrt{6}}{3}$
(≈10.73009)
Reference unknown
[via Circles in Triangles, Erich Friedman] -
1994-12-01
Lower bound: $4+2\sqrt{3}+\frac{4\sqrt{6}}{3}$
(≈10.73009)
Melissen, J. B. M. (1994). Optimal packings of eleven equal circles in an equilateral triangle. Acta Mathematica Hungarica, 65(4), 389-393.
[via Circles in Triangles, Erich Friedman]