Let ABCDEF be a convex hexagon satisfying AB∥DE , BC∥EF , CD∥FA , and
AB⋅DE=BC⋅EF=CD⋅FA.
Let X , Y , and Z be the midpoints of AD , BE , and CF . Prove that the circumcenter of △ACE , the circumcenter of △BDF , and the orthocenter of △XYZ are collinear.