MathDB
Inequality => square

Source: INMO 1998 Problem 4

October 7, 2005
trigonometrygeometryrectanglecyclic quadrilateralgeometric inequality

Problem Statement

Suppose ABCDABCD is a cyclic quadrilateral inscribed in a circle of radius one unit. If AB⋅BC⋅CD⋅DA≥4AB \cdot BC \cdot CD \cdot DA \geq 4, prove that ABCDABCD is a square.
Back to ProblemsView on AoPS