Gogeometry Problem 241 dans Euclide Geometry Problem par Harvey Littleman From Gogeometry : Using : Congruent Triangles Equilateral triangle ∠CBC’=∠ABC+∠ABC’= ∠ABC+60° ∠ABA’= ∠ABC+∠CBA’= ∠ABC+60° =>∠CBC’=∠ABA’ ΔABA’ is congruent to ΔCBC’ (SAS) Therefore AA’=CC’