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MathNet 2018-part-06 — 181 problems (EN–VI) Question 109

Math Olympiad Vault · MathNet 2018-part-06 — 181 problems (EN–VI)

Question 109

Consider a triangle $ABC$ and a line that does not coincide with the triangle sides and passes through the point $A$. This line meets altitudes $BH_2$ and $CH_3$ at the points $D_1$ and $E_1$, respectively. By $D_2$ and $E_2$ we denote points that are symmetrical to $D_1$ and $E_1$ with respect to the sides $AB$ and $AC$, respectively. Prove that the circumcircle of the triangle $D_2AB$ is tangent to the circumcircle of the triangle $E_2AC$.

(Myhailo Plotnikov)