MathDB
Lattice triangles with certain properties

Source: Kvant Magazine No. 9 2020 M2619

March 9, 2023
geometrylattice pointsKvant

Problem Statement

Let abca\leqslant b\leqslant c be non-negative integers. A triangle on a checkered plane with vertices in the nodes of the grid is called an (a,b,c)(a,b,c)-triangle if there are exactly aa{} nodes on one side of it (not counting vertices), exactly bb{} nodes on the second side, and exactly cc{} nodes on the third side.
[*]Does there exist a (9,10,11)(9,10,11)-triangle? [*]Find all triples of non-negative integers abca\leqslant b\leqslant c for which there exists an (a,b,c)(a,b,c)-triangle. [*]For each such triple, find the minimum possible area of the (a,b,c)(a,b,c)-triangle.
Proposed by P. Kozhevnikov