MathDB
Inequality

Source: Chinese TST

April 6, 2008
inequalitiesgeometrycircumcircletrigonometryratiocyclic quadrilateralgeometry proposed

Problem Statement

Let PP be an arbitrary point inside triangle ABCABC, denote by A1A_{1} (different from PP) the second intersection of line APAP with the circumcircle of triangle PBCPBC and define B1,C1B_{1},C_{1} similarly. Prove that \left(1 \plus{} 2\cdot\frac {PA}{PA_{1}}\right)\left(1 \plus{} 2\cdot\frac {PB}{PB_{1}}\right)\left(1 \plus{} 2\cdot\frac {PC}{PC_{1}}\right)\geq 8.