# Dynamic Geometry: Exeter Point, Triangle, Median, Circumcircle, Concurrent Lines, Euler Line, GeoGebra, HTML5 Animation for Tablets (iPad, Nexus, Samsung). Levels: School, College, Mathematics Education

 Given a triangle ABC (see the dynamic figure below),  Medians AA1, BB1, and CC1, meet the circumcircle O at A2, B2, and C2, respectively. Tangents at A, B, and C form a triangle A3B3C3. Prove that (1) Lines A3A2, B3B2, and C3C2 are concurrent at a point E, called the Exeter point. (2) E lies on the Euler line.  See also: Exeter Point Puzzle. Reference Kimberling, Clark. "Encyclopedia of Triangle Centers: X(22)" Dynamic Geometry Environment (DGE) or Interactive Geometry Software (IGS) of the Exeter Point The interactive demonstration above was created with GeoGebra. To stop/play the animation: tap the icon in the lower left corner. To reset the interactive figure to its initial state: tap the icon in the upper right corner. To manipulate the interactive figure: tap and drag points or lines.    GeoGebra GeoGebra is free and multi-platform dynamic mathematics software for all levels of education that joins geometry, algebra, tables, graphing, statistics and calculus application, intended for teachers and students.  Static Diagram of Exeter Point
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