no of lines passing through 2 or 3 centers of 27 unit cubes of a 3x3 cube
Source: 1990 ITAMO p1
January 31, 2020
combinatoricscubecombinatorial geometrygeometry3D geometry
Problem Statement
A cube of edge length consists of unit cubes. Find the number of lines passing through exactly three centers of these cubes, as well as the number of those passing through exactly two such centers.