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PrintSELECTION 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