Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2vC/ Esercizi: http://www.khanacademy.org/exercise/inverse_trig_functions Traduzione in Italiano del video Inverse Trig Functions: Arccos http://www.youtube.com/watch?feature=player_embedded&v=eTDaJ4ebK28 http://www.khanacademy.org/video/inverse-trig-functions--arccos?topic=trigonometry Help us caption & translate this video! http://amara.org/v/B2vC/