Packing $7$ 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 $7$ unit circles can be packed.
Value: $2+4\sqrt{3}$ (≈8.928203)
Updates
-
Upper bound: $2+4\sqrt{3}$
(≈8.928203)
Reference unknown
[via Circles in Triangles, Erich Friedman] -
1993-12
Lower bound: $2+4\sqrt{3}$
(≈8.928203)
Melissen, H. (1993). Densest packings of congruent circles in an equilateral triangle. The American Mathematical Monthly, 100(10), 916-925.
[via Circles in Triangles, Erich Friedman]