Geometry
Problem 993: Intersecting Circles, Secant, Tangent,
Concyclic Points, Cyclic Quadrilateral,
Perpendicular.
Level: School, College
The circles O and Q intersect at A and B
(see the figure) and CAD is a secant line. The tangents at C and D meet
at E. CO ad DQ extended meet at F. Prove that (1) Points O, F, B, and Q
are concyclic; (2) FB is perpendicular to EB.