P11 · Packing and covering · Classic

Equal-circle packing in a right triangle

0.75y0
0x1
VERIFIED CONSTRUCTIONr = 0.119982102
n = 5Current record · open

Place n non-overlapping equal circles inside the right triangle with legs 1 and 0.75, making the common radius as large as possible.

Formal definition

  • ContainerA right triangle: the right angle at the origin (0, 0), one leg along the x-axis to (1, 0), the other along the y-axis to (0, 0.75)
  • SubmissionExactly n circles: one shared radius and n centres
  • ConstraintsEvery circle lies wholly inside the container; no two overlap in their interiors, tangency allowed
  • ObjectiveMake the common radius as large as possible

Getting a feel for it

Where the room for improvement is

Optimal packings are jammed contact structures: circles brace against each other and the boundary, with tilted rows, offsets, and the odd rattler touching nothing. Neat grids are almost never optimal.

Where the frontier is

This particular triangle, legs 1 and 0.75, has no literature table; close relatives such as the isosceles right triangle are collected on Friedman's Packing Center. No values are recorded here, and every n is open.

Source
ONE LEADERBOARD PER n

Current best solutions by n

Each n is an independent record with a page of its own. Open any of them to inspect the current construction, then challenge it.