AB + BD > AC + CD in cyclic ABCD, AB is the longest side
Source: 49th Austrian Mathematical Olympiad National Competition (Final Round, part 2, ) 31st May 2018 p2
May 25, 2019
geometric inequalitygeometrycyclic quadrilateral
Problem Statement
Let and be four different points lying on a common circle in this order. Assume that the line segment is the (only) longest side of the inscribed quadrilateral . Prove that the inequality holds.(Proposed by Karl Czakler)