MathDB

4

Part of 1998 India National Olympiad

Problems(1)

Inequality => square

Source: INMO 1998 Problem 4

10/7/2005
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.
trigonometrygeometryrectanglecyclic quadrilateralgeometric inequality