sinα=√5/5cosα=2√5/5tanβ=1/3sinβ=√10/10cosβ=3√10/10sin(α+β)=sinαcosβ+cosαsinβ=√5/5*3√10/10+2√5/5*√10/10=3√50/50+2√50/50=5√50/50=25√2/50=√2/2α+β=45°或135° 因为tanβ=1/3,β...