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ratio of areas, hexagon / triangle : G/F>13

Source: 1993 German Federal - Bundeswettbewerb Mathematik - BWM - Round 1 p4

November 20, 2022
ratiogeometric inequalityareasgeometry

Problem Statement

Given is a triangle ABCABC with side lengths a,b,ca, b, c (a=BCa = \overline{BC}, b=CAb = \overline{CA}, c=ABc = \overline{AB}) and area FF. The side ABAB is extended beyond AA by a and beyond BB by bb. Correspondingly, BCBC is extended beyond BB and CC by bb and cc, respectively. Eventually CACA is extended beyond CC and AA by cc and aa, respectively. Connecting the outer endpoints of the extensions , a hexagon if formed with area GG. Prove that GF>13\frac{G}{F}>13.