⑴据万能公式有：sin2α=2tanα/(1+tan^2α)=3/5,所以,（sinα+cosα)^2=1+sin2α=8/5⑵由于cos^2α=1/sec^2α=1/(1+tan^2α)=9/10,1/2sin2α=tanα/(1+tan^2α)=-(1/3)/(10/9)=-3/10所以,原式＝-3/10+9/10=3/5...