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MathNet 2008-part-03 — 165 problems (EN–VI) Question 152

Math Olympiad Vault · MathNet 2008-part-03 — 165 problems (EN–VI)

Question 152

In the triangle $ABC$ the lengths of the sides are given: $|AB| = 15$ cm, $|BC| = 14$ cm and $|CA| = 13$ cm. Let $D$ be the foot of the altitude from $A$ and let $E$ be a point on this altitude such that $\angle BAD = \angle DEC$. Denote the intersection of lines $AB$ and $CE$ by $F$. Find $|EF|$.