tan(π+α)=tanα=-1/3.tanα^2=[(sinα)^2]/[(cosα)^2]=1/9而(sinα)^2+(cosα)^2=1,所以解得(sinα)^2=1/10,(cosα)^2=9/10简化tan（α+β）=[sin2（π/2-α）+4（cosα）^2]/[10(cosα)^2-sin2α]tan（α+β）=[...