Go Geometry Problems

Dynamic Geometry Problem 900: Intersecting Circles, Common External Tangent, Secant, Angle, Congruence. GeoGebra, HTML5 Animation for Tablets (iPad, Nexus). Levels: School, College, Mathematics Education

Dynamic Geometry Problem 900: Intersecting Circles, Common External Tangent, Secant, Angle, Congruence. 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. If FC and ED intersect at G, prove that angles ABC and DBG are congruent.
 

Dynamic Geometry Environment (DGE) or Interactive Geometry Software (IGS) of Problem 900

The interactive demonstration below 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. 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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