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 FG at H. If the circumcircle of
triangle EFG intersects circle O1 at J, prove that the points
B, C, H, J are concyclic.
Dynamic Geometry Environment (DGE) or Interactive Geometry Software
(IGS) of Problem 901
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Solution/Comment | by Antonio Gutierrez