MathDB

17

Part of 1988 IMO Shortlist

Problems(1)

IMO ShortList 1988 regular pentagon

Source: IMO ShortList 1988, Problem 17, Israel 2, Problem 47 of ILL

11/3/2005
In the convex pentagon ABCDE, ABCDE, the sides BC,CD,DE BC, CD, DE are equal. Moreover each diagonal of the pentagon is parallel to a side (AC AC is parallel to DE DE, BD BD is parallel to AE AE etc.). Prove that ABCDE ABCDE is a regular pentagon.
geometryconvex polygonpentagonanglesIMO Shortlist