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MathNet 2019-part-03 — 184 problems (EN–VI) Question 18

Math Olympiad Vault · MathNet 2019-part-03 — 184 problems (EN–VI)

Question 18

Let a triangle $A B C$ with circumcircle $\Omega$ be given, together with points $A_{1}, B_{1}$ and $C_{1}$ on the sides $\overline{B C}, \overline{C A}$ and $\overline{A B}$ such that the three lines $A A_{1}, B B_{1}$ and $C C_{1}$ have a point $P$ in common.
Prove that at most two of the three reflections of $P$ in the points $A_{1}$, $B_{1}$ and $C_{1}$ (point reflections) lie outside $\Omega$.