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TSTST 2018 Problem 5

    Let ABCA B C be an acute triangle with circumcircle ω\omega, and let HH be the foot of the altitude from AA to BC‾\overline{B C}. Let PP and QQ be the points on ω\omega with PA=PHP A=P H and QA=QHQ A=Q H. The tangent to ω\omega at PP intersects lines ACA C and ABA B at E1E_{1} and F1F_{1} respectively; the tangent to ω\omega at QQ intersects lines ACA C and ABA B at E2E_{2} and F2F_{2} respectively. Show that the circumcircles of △AE1F1\triangle A E_{1} F_{1} and △AE2F2\triangle A E_{2} F_{2} are congruent, and the line through their centers is parallel to the tangent to ω\omega at AA.

    Dataset text NuminaMath olympiads. Quoted with source.

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