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Sum of Radii

Author:John Golden
Topic:Circle, Incircle or Inscribed Circle
Inscribe a polygon in a circle, and any triangulation has a surprising property - the sum of the radii of the incircles is constant! First seen as a sangaku, circa 1800. Via Futility Closet: http://www.futilitycloset.com/2015/01/08/cutting-up/

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