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MathNet 2018-part-01 — 181 problems (EN–VI) Question 103

Math Olympiad Vault · MathNet 2018-part-01 — 181 problems (EN–VI)

Question 103

The point $X$ is marked inside the triangle $ABC$. The circumcircles of the triangles $AXB$ and $AXC$ intersect the side $BC$ again at $D$ and $E$ respectively. The line $DX$ intersects the side $AC$ at $K$, and the line $EX$ intersects the side $AB$ at $L$.
Prove that $LK \parallel BC$.