MathDB

3

Part of 2018 Czech and Slovak Olympiad III A

Problems(1)

Circumcenters

Source: Czech and Slovak Olympiad 2018, National Round, Problem 3

4/5/2018
In triangle ABCABC let be DD an intersection of BCBC and the AA-angle bisector. Denote E,FE,F the circumcenters of ABDABD and ACDACD respectively. Assuming that the circumcenter of AEFAEF lies on the line BCBC what is the possible size of the angle BACBAC ?
geometrynational olympiadcircumcircle