Cerchi: Raggio Diametro e Circonferenza

Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2vv/ Esercizi: http://www.khanacademy.org/exercise/geometry_1 Traduzione in Italiano del video Circles: Radius, Diameter and Circumference http://www.youtube.com/watch?feature=player_embedded&v=jyLRpr2P0MQ http://www.khanacademy.org/video/circles--radius--diameter-and-circumference?playlist=Geometry Help us caption & translate this video! http://amara.org/v/B2vv/