Dimostrazione: sin(a+b) = (cos a)(sin b) + (sin a)(cos b)

Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2v8/ Esercizi: http://www.khanacademy.org/exercise/trig_identities_1 Traduzione in Italiano del video: Proof: sin(a+b) = (cos a)(sin b) + (sin a)(cos b) http://www.youtube.com/watch?feature=player_embedded&v=zw0waJCEc-w http://www.khanacademy.org/video/proof--sin-a-b------cos-a--sin-b-----sin-a--cos-b?playlist=Trigonometry