Italian WinterCamps test07 Problem4
Source: ISL 2006, G3, VAIMO 2007/5
January 29, 2007
geometrycircumcirclepentagonIMO Shortlist
Problem Statement
Let be a convex pentagon such that
\angle BAC \equal{} \angle CAD \equal{} \angle DAE\qquad \text{and}\qquad \angle ABC \equal{} \angle ACD \equal{} \angle ADE.
The diagonals and meet at . Prove that the line bisects the side .Proposed by Zuming Feng, USA