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MathNet 2026 — Part 08 Question 24

Math Olympiad Vault · MathNet 2026 — Part 08

Question 24

Circles $w_1$ and $w_2$ centered at points $O_1$ and $O_2$ respectively intersect at points $A$ and $B$. Let $w$ be the circumscribed circle of $O_1O_2B$ centered at $O$, which intersects $w_1$ and $w_2$ again at points $K$ and $L$ respectively. The straight line $OA$ intersects $w_1$ and $w_2$ at points $M$ and $N$ respectively. Denote by $P$ the intersection point of lines $MK$ and $NL$. Prove that $P$ lies on $w$ and $PM = PN$.
(Vadym Mytrofanov)