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MathNet 2024-part-04 — 168 problems (EN–VI) Question 130

Math Olympiad Vault · MathNet 2024-part-04 — 168 problems (EN–VI)

Question 130

Let $\triangle ABC$ be a triangle with $\angle BAC = 30^\circ$ and $\angle ABC = 100^\circ$. Let $m$ be the perpendicular bisector of $AC$, $E$ be the intersection of $m$ and $AB$, and $D$ be the point on $m$, inside the triangle $ABC$, such that $\angle CAD = 10^\circ$. Let $M$ be the intersection of the lines $AD$ and $CE$.

a) Prove that $CE$ is the bisector of the angle $\angle BCD$.

b) Prove that $AM = AB$.