IMO 2017 Shortlist G1

Let ABCDE be a onvex pentagon su h that AB “ BC “ CD, =EAB “ =BCD, and =EDC “ =CBA. Prove that the perpendi ular line fr...

imomathematicsolympiadshortlistgeometry

IMO 2017 Shortlist G1

Category: Geometry

Problem

Let ABCDE be a onvex pentagon su h that AB “ BC “ CD, =EAB “ =BCD, and =EDC “ =CBA. Prove that the perpendi ular line from E to BC and the line seg- ments AC and BD are on urrent. (Italy)