olymmath

CN-LEAGUE 2009 Problem 1

    Let ω\omega be the circumcircle of acute triangle ABCABC where ∠A<∠B\angle A<\angle B and M,NM,N be the midpoints of minor arcs BC,ACBC,AC of ω\omega respectively. The line PCPC is parallel to MNMN , intersecting ω\omega at PP (different from CC ). Let II be the incentre of ABCABC and let PIPI intersect ω\omega again at the point TT .

    1. Prove that MP⋅MT=NP⋅NTMP\cdot MT=NP\cdot NT ;
    2. Let QQ be an arbitrary point on minor arc ABAB and I,JI,J be the incentres of triangles AQC,BCQAQC,BCQ . Prove that Q,I,J,TQ,I,J,T are concyclic.

    Dataset text AI-MO AoPS. Quoted with source.

    Solutions

    No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.

    Add a solution

    Similar problems

    These problems have the most words in common with this statement.

    Locator cn-league/2009/p1 · Tag 8C48CS0VEC · Edit this page on GitHub · Keys: j next, k previous