For a triangle ABC with circumcircle c1 and internal angle bisector BD (see diagram) let EF be perpendicular to BD, GH perpendicular bisector of AE, and JK perpendicular bisector of CF. Chord HL passes through E and chord KM passes through F, Prove that (1) Points M, E, F, and L are concyclic; (2) EF and HK are parallel.
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Ten problems: 1411-1420
HTML5 and Dynamic Geometry
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