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MathNet 2006 — Part 02 Question 124

Math Olympiad Vault · MathNet 2006 — Part 02

Question 124

the incircle $k$ of $\triangle ABC$ is tangent to the sides $AB$, $BC$ and $CA$ at points $C_1$, $A_1$ and $B_1$, respectively. The points $C_2$, $A_2$ and $B_2$ are diametrically opposite to $C_1$, $A_1$ and $B_1$ in $k$.


a) Prove that the lines $AA_2$, $BB_2$ and $CC_2$ are concurrent.


b) If the line $AA_2$ meets $k$ at $A_3$, find the ratio in which the tangent line to $k$ at $A_3$ divides $BC$.