MathDB
Geometric ineq. (IMO SL 1987-P4)

Source:

August 19, 2010
geometrygeometric inequality3D geometrypolyhedronIMO Shortlist

Problem Statement

Let ABCDEFGHABCDEFGH be a parallelepiped with AEBFCGDHAE \parallel BF \parallel CG \parallel DH. Prove the inequality AF+AH+ACAB+AD+AE+AG.AF + AH + AC \leq AB + AD + AE + AG. In what cases does equality hold?
Proposed by France.