Geometry Problem 1456: Altitudes, Orthic Triangle, Circumcircle, Parallel, Similarity, Area

Let AHA, BHB, CHC be the altitudes of a triangle ABC. The extensions of AHA, BHB, CHC intersect the circumcircle O at A1, B1, C1. Prove that (1) HAHB // A1B1, similarly HBHC // B1C1, HAHC // A1C1; (2) Area A1, B1C1.


Static Diagram of problem 1456

Dynamic Geometry 1456: Altitude, Orthic Triangle, Circumcircle, Similarity, Area. Using GeoGebra


Poster of the problem 1456 using iPad Apps

Poster of Problem 1456, Altitude, Orthic Triangle, Circumcircle, Similarity, Area. Using iPad

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