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MathNet 2019-part-06 — 184 problems (EN–VI) Question 160

Math Olympiad Vault · MathNet 2019-part-06 — 184 problems (EN–VI)

Question 160

In the scalene triangle $ABC$, the bisector of angle $A$ meets side $BC$ at the point $D$. The lines passing through $D$ that are tangent to the circumcircles of triangles $ABD$ and $ACD$ meet the lines $AC$ and $AB$ at the points $E$ and $F$, respectively. If $BE$ and $CF$ meet at $G$, prove that the angles $\angle EDG$ and $\angle ADF$ are equal.