Skip to main content
OlympiadHQ

Browse · MathNet

Print

SELECTION and TRAINING SESSION

Belarus geometry

Problem

Points , , lie on the sides , , of a triangle , respectively, so that , , meet at a common point. Let , , , be the inradii of the triangles , , , , respectively. Prove that or or .
Solution
2. See IMO-2014 Shortlist, Problem G2.

Techniques

Triangle centers: centroid, incenter, circumcenter, orthocenter, Euler line, nine-point circleCeva's theoremTangentsTriangle inequalities