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AZE JBMO TST

Source: AZE JBMO TST

May 2, 2015
geometrycircumcircleAZE JBMO TST

Problem Statement

Let ABCABC be a triangle such that ABAB is not equal to ACAC. Let MM be the midpoint of BCBC and HH be the orthocenter of triangle ABCABC. Let DD be the midpoint of AHAH and OO the circumcentre of triangle BCHBCH. Prove that DAMODAMO is a parallelogram.
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