MathDB
n + 1 points at each edge of a tetrahedron

Source: Rioplatense 1995 L3 P3

September 19, 2022
geometry3D geometrycombinatoricstetrahedroncombinatorial geometry

Problem Statement

Given a regular tetrahedron with edge aa, its edges are divided into nn equal segments, thus obtaining n+1n + 1 points: 22 at the ends and n1n - 1 inside. The following set of planes is considered: \bullet those that contain the faces of the tetrahedron, and \bullet each of the planes parallel to a face of the tetrahedron and containing at least one of the points determined above. Now all those points PP that belong (simultaneously) to four planes of that set are considered. Determine the smallest positive natural nn so that among those points PP the eight vertices of a square-based rectangular parallelepiped can be chosen.