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, BA intersects CD at H. If O2 is the circumcenter of triangle CGD, prove that
the points G, O2, and H are collinear.
Dynamic Geometry of Problem 898
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 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.
Search | Geometry
All Problems |
Problems Art Gallery
Nexus 7 Apps
Solution/Comment | by Antonio Gutierrez