IMO 1985 LL MOR56

Let ABCD be a rhombus with angle ngleA = 60◦. Let E be a

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IMO 1985 LL MOR56

Origin: MOR

Problem

Let ABCD be a rhombus with angle \angleA = 60◦. Let E be a point, different from D, on the line AD. The lines CE and AB intersect at F. The lines DF and BE intersect at M. Determine the angle ∡BMD as a function of the position of E on AD.