isosceles trapezoid criterion, sum of lengths of sides and diagonals related
Source: 2007 Oral Moscow Geometry Olympiad grades 10-11 p3
October 19, 2020
geometrytrapezoidisosceles
Problem Statement
In a trapezoid, the sum of the lengths of the side and the diagonal is equal to the sum of the lengths of the other side and the other diagonal. Prove that the trapezoid is isosceles.