Problem

Source: (2021 -) 2022 Dürer Math Competition Regional E+2 https://artofproblemsolving.com/community/c1621671_

Tags: combinatorial geometry, congruent triangles, geometry



Determine all triangles that can be split into two congruent pieces by one cut. A cut consists of segments $P_1P_2$, $P_2P_3$, . . . , $P_{n-1}P_n$ where points $P_1, P_2, . . . , P_n$ are distinct, points $P_1$ and $P_n$ lie on the perimeter of the triangle and the rest of the points lie in the interior of the triangle such that the segments are disjoint except for the endpoints.