olymmath

JBMO 2021 Problem 3

  • Paper

Let ABCA B C be an acute scalene triangle with circumcenter OO. Let DD be the foot of the altitude from AA to the side BCB C. The lines BCB C and AOA O intersect at EE. Let ss be the line through EE perpendicular to AOA O. The line ss intersects ABA B and ACA C at KK and LL, respectively. Denote by ω\omega the circumcircle of triangle AKLA K L. Line ADA D intersects ω\omega again at XX.

Prove that ω\omega and the circumcircles of triangles ABCA B C and DEXD E X have a common point.

Dataset text NuminaMath olympiads. Quoted with source.

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