Dynamic
Geometry Problem 987:
Triangle, Circumcircle, Incenter, Chord, Parallel,
Circle, Tangent. GeoGebra, HTML5 Animation for Tablets (iPad, Nexus). Levels:
School, College, Mathematics Education
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The dynamic figure below shows a triangle ABC
with the incenter I. AI and BI extended meet the circumcircle C_{o} of
triangle ABC at D and E, respectively. DE meets AC at F, chord EG is
parallel to FI, FI extended meets DG at K. Prove that the circumcircle of triangle
DFK is tangent to circle C_{o}, AC and BK at D, F, and K, respectively.
