Packing $1$ 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 $1$ unit circles can be packed.
Value: $2\sqrt{3}$ (≈3.464102)
Updates
-
Lower bound: $2\sqrt{3}$
(≈3.464102)
Trivial or easy according to the secondary source.
[via Circles in Triangles, Erich Friedman] -
Upper bound: $2\sqrt{3}$
(≈3.464102)
Trivial or easy according to the secondary source.
[via Circles in Triangles, Erich Friedman]