Problem A. 549. (December 2011)
A. 549. The diagonals of a circumscribed quadrilateral ABCD meet at E. Show that the incenters of the triangles ABE, BCE, CDE and DAE lie on a circle.
(Proposed by: G. Holló, Budapest)
Deadline expired on January 10, 2012.
3 students sent a solution. 5 points: Gyarmati Máté, Mester Márton, Omer Cerrahoglu.