Disk covering problem

The disk covering problem asks for the smallest real number $r(n)$ such that $n$ disks of radius $r(n)$ can be arranged in such a way as to cover the unit disk. Dually, for a given radius ε, one wishes to find the smallest integer n such that n disks of radius ε can cover the unit disk.

The best solutions to date are as follows:

n	r(n)
1	1
2	1
3	${\sqrt {3}}/2$
4	${\sqrt {2}}/2$
5	0.609382...
6	0.555905...
7	$1/2$
8	0.445041...
9	0.414213...
10	0.394930...

Method

This is the best known layout strategy for r(9) and r(10):

External links

• Weisstein, Eric W. "Disk Covering Problem." From MathWorld—A Wolfram Web Resource. http://mathworld.wolfram.com/DiskCoveringProblem.html
• Finch, S. R. "Circular Coverage Constants." §2.2 in Mathematical Constants. Cambridge, England: Cambridge University Press, pp. 484–489, 2003.
• Illustrations of circles covering circles