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can from any point of the AB section one see the whole museum?

Source: 2021 Dürer Math Competition Regional E3 https://artofproblemsolving.com/community/c2773609_2021_

January 7, 2022
geometrypolygon

Problem Statement

The floor plan of a contemporary art museum is a (not necessarily convex) polygon and its walls are solid. The security guard guarding the museum has two favourite spots (points AA and BB) because one can see the whole area of the museum standing at either point. Is it true that from any point of the ABAB section one can see the whole museum?