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MathNet 2025-part-02 — 186 problems (EN–VI) Question 54

Math Olympiad Vault · MathNet 2025-part-02 — 186 problems (EN–VI)

Question 54

Consider a triangle $ABC$ with $AC \gt AB$ and $\angle ACB = 60^\circ$. Let $D$ be a point on side $BC$ such that $AD$ is the angle bisector of $\angle BAC$ and $AB = AD$. Point $E$ lies on line $AD$ such that $D$ is between $A$ and $E$, and $AE = AC$. Point $F$ lies on line $AB$ such that $B$ is between $A$ and $F$. Point $T$ is on segment $AE$ such that $BF = TE = CD$. Show that:

a) $EF = CT$;

b) $AC = BC + BT$.