Dynamic Geometry
The interactive figure above, created with GeoGebra,
shows a triangle ABC with the Lemoine Line C_{1}A_{1}B_{1}.
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Lemoine Line
Tangents to the circumcircle of triangle ABC, at points A, B, and C, meet sides BC, AC, and BA at points
C_{1}A_{1}, and B_{1}, respectively. Prove that points
C_{1}A_{1}B_{1} are collinear.
GeoGebra
GeoGebra is free and multiplatform dynamic mathematics software for all levels of education that joins geometry, algebra, tables, graphing, statistics and calculus
application, intended for teachers and students. Many parts of GeoGebra have
been ported to HTML5. It has received several educational software awards in Europe and the USA.
