Geometry Problem 893:
Triangle, Circumcircle, Incenter, Circle, Tangent,
Collinear Points. GeoGebra, HTML5 Animation for Tablets (iPad, Nexus). Levels:
School, College, Mathematics Education
The dynamic figure below shows a triangle
ABC with incenter I. Circle of center C and radius CB intersects AC at
D. Tangent to the circumcircle O intersects circle C at E. Prove that
the points D, I, and E are collinear.