super nice 6-th problem, an interesting result.
Source: Third Zhautykov Olympiad, Kazakhstan, 2007
April 25, 2007
geometrycircumcircletrapezoidtrigonometrygeometric transformationhomothetyratio
Problem Statement
Let be a convex hexagon and it`s diagonals have one common point . It is known that the circumcenters of triangles lie on a circle.
Show that the quadrilaterals have equal areas.