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MathNet 2009-part-03 — 175 problems (EN–VI) Question 53

Math Olympiad Vault · MathNet 2009-part-03 — 175 problems (EN–VI)

Question 53

Let $\triangle ABC$ be an equilateral triangle. Let $C_1$ and $C_2$ be on $AB$, $B_1$ and $B_2$ on $AC$ and $A_1$ and $A_2$ on $BC$ such that $\overline{A_1A_2} = \overline{B_1B_2} = \overline{C_1C_2}$. Let $A_2B_1$ and $B_2C_1$, $B_2C_1$ and $C_2A_1$, $C_2A_1$ and $A_2B_1$ intersect at $E$, $F$, $G$ correspondently. Prove that the triangle formed by the segments $B_1A_2$, $A_1C_2$ and $C_1B_2$ is similar to $\triangle EFG$.

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