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MathNet 2015-part-05 — 191 problems (EN–VI) Question 10

Math Olympiad Vault · MathNet 2015-part-05 — 191 problems (EN–VI)

Question 10

Consider a triangle $ABC$, such that $\angle B = 90^\circ$. Denote by $I$ the in-center and let $F$, $D$ and $E$ be the points where the incircle touches sides $[AB]$, $[BC]$, and $[AC]$ respectively. If $CI \cap EF = \{M\}$ and $DM \cap AB = \{N\}$, show that:

a) $AI = ND$;

b) $FM = \frac{EI \cdot EM}{EC}$.