Geometry Problem 246. Napoleon's Theorem I. External Equilateral triangles. Outer triangle.
Online High School, College, SAT Prep.
In the figure, equilateral triangles ABC', BCA', and ACB' are constructed externally on the sides of a triangle ABC. Prove that the centers A_{1}, B_{1}, and C_{1} of those equilateral triangles form an equilateral triangle, called the outer Napoleon triangle. View or post a solution.
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