MathDB
3 isosceles given on a line with an angle 120, equilateral wanted

Source: 1999 German Federal - Bundeswettbewerb Mathematik - BWM - Round 1 p3

January 27, 2020
geometryisoscelesEquilateral

Problem Statement

In the plane are given a segment ACAC and a point BB on the segment. Let us draw the positively oriented isosceles triangles ABS1,BCS2ABS_1, BCS_2, and CAS3CAS_3 with the angles at S1,S2,S3S_1,S_2,S_3 equal to 120o120^o. Prove that the triangle S1S2S3S_1S_2S_3 is equilateral.
Back to ProblemsView on AoPS