Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2wP/ Traduzione in Italiano del video Foci of a Hyperbola http://www.youtube.com/watch?v=S0Fd2Tg2v7M http://www.khanacademy.org/video/foci-of-a-hyperbola?playlist=Algebra