Go Geometry Problems

Dynamic Geometry Problem 899: Intersecting Circles, Common External Tangent, Secant, Concyclic Points, Cyclic Quadrilateral. GeoGebra, HTML5 Animation for Tablets (iPad, Nexus). Levels: School, College, Mathematics Education

Dynamic Geometry Problem 899: Intersecting Circles, Common External Tangent, Secant, Concyclic Points. HTML5 Animation for Tablets


 

The circles O and O1 intersect at A and B (see the figure above), CD is the common external tangent, CA intersects circle O1 at E, DA intersects circle O at F, FC and ED intersect at G. Prove that the points B,C,G,E are concyclic, similarly B,D,G,F are concyclic.
 

Dynamic Geometry of Problem 899

The interactive demonstration below was created with GeoGebra.

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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. Many parts of GeoGebra have been ported to HTML5. It has received several educational software awards in Europe and the USA.
 

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