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MathNet 2026 — Part 06 Question 74

Math Olympiad Vault · MathNet 2026 — Part 06

Question 74

Consider the points $B$, $N$, $M$, $C$ in this order on a line, such that
$$
|BC| = 2|BM| = 4|BN|.
$$
The perpendiculars on $BC$ raised from $N$ and $M$ meet a line through $C$ at the points $A$ and $E$, respectively. Let $D$ be the intersection of $AM$ and $BE$. Prove the following statements:


a. Line $AC$ is tangent to the circumcircle of $\triangle ADB$.


b. The point $D$ is the midpoint of $AM$.