Packing $12$ unit circles in an equilateral triangle
OwOUwUOwU, via Wikimedia Commons. CC BY-SA 4.0.
The side length of the smallest equilateral triangle into which $12$ unit circles can be packed.
Value: $4+4\sqrt{3}$ (≈10.9282)
Updates
-
Upper bound: $4+4\sqrt{3}$
(≈10.9282)
Reference unknown
[via Circles in Triangles, Erich Friedman] -
1994
Lower bound: $4+4\sqrt{3}$
(≈10.9282)
Melissen in 1994
[via Circles in Triangles, Erich Friedman]