Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2v7/ Esercizi: http://www.khanacademy.org/exercise/trig_identities_1 Traduzione in Italiano del video Trigonometric Identities http://www.youtube.com/watch?feature=player_embedded&v=OLzXqIqZZz0 http://www.khanacademy.org/video/trigonometric-identities?playlist=Trigonometry Help us caption & translate this video! http://amara.org/v/B2v7/