MathDB
ABC

Source: SRMO 2005

April 10, 2005
geometrycircumcircletrigonometrypower of a pointradical axissimilar trianglesgeometry proposed

Problem Statement

Assume A,B,CA,B,C are three collinear points that B[AC]B \in [AC]. Suppose AAAA' and BBBB' are to parrallel lines that AA', BB' and CC are not collinear. Suppose O1O_1 is circumcenter of circle passing through AA, AA' and CC. Also O2O_2 is circumcenter of circle passing through BB, BB' and CC. If area of ACBA'CB' is equal to area of O1CO2O_1CO_2, then find all possible values for CAA\angle CAA'