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AREA in terms of S.

Source: JBMO 2014, pr 2

June 23, 2014
geometryanalytic geometryparallelogramcircumcircle

Problem Statement

Consider an acute triangle ABCABC of area SS. Let CDABCD \perp AB (DABD \in AB), DMACDM \perp AC (MACM \in AC) and DNBCDN \perp BC (NBCN \in BC). Denote by H1H_1 and H2H_2 the orthocentres of the triangles MNCMNC, respectively MNDMND. Find the area of the quadrilateral AH1BH2AH_1BH_2 in terms of SS.