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here is a regular n-gon whose all vertices lie on the considered arcs

Source: Romania IMO TST 1991 p6

February 19, 2020
combinatoricscombinatorial geometry

Problem Statement

Let n3n \ge 3 be an integer. A finite number of disjoint arcs with the total sum of length 11n1 -\frac{1}{n} are given on a circle of perimeter 11. Prove that there is a regular nn-gon whose all vertices lie on the considered arcs