Circles Covering Triangles

The following pictures show n unit circles covering the largest known equilateral triangle (of side s ).


1.            2.            3.
s = √3 = 1.732+
Trivial.
s = 2
Trivial.
s = 2√3 = 3.464+
Trivial.


4.            5.            6.
s = 2 + √3 = 3.732+
Proved by Hans Melissen
in 1997.
s = 4
Proved by Hans Melissen
in 1997.
s = 3√3 = 5.196+
Proved by Hans Melissen
in 1997.


7.            8.            9.
s = 5.398+
Found by P. Schuur
in 1997.
s = 5.649+
Found by P. Schuur
in 1997.
s = 6
Proved by Hans Melissen
in 1997.