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MathNet 2013 Question 98

Math Olympiad Vault · MathNet 2013

Question 98

Circle ω passes through vertices B,C of triangle ABC and meets sides AB,AC again at D,E respectively. Segments CD and BE intersect at O. Let M,N be the incenters of triangles ADE and ODE respectively. Prove that the midpoint of the smaller arc DE of ω lies on line MN.