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Triangles into each other

Source: Iran TST 2015 Test 3 Day 2 P1

August 18, 2023
geometry

Problem Statement

Ali puts 55 points on the plane such that no three of them are collinear. Ramtin adds a sixth point that is not collinear with any two of the former points.Ali wants to eventually construct two triangles from the six points such that one can be placed inside another. Can Ali put the 5 points in such a manner so that he would always be able to construct the desired triangles? (We say that triangle T1T_1 can be placed inside triangle T2T_2 if T1T_1 is congruent to a triangle that is located completely inside T2T_2.)