sinα=1/3,cos(α+β)=1cosα=±√(1-sin²α)=±2√2/3sin(α+β)=±√[1-cos²(α+β)]=0sin(2α+β)=sin[α+(α+β)]=sinαcos(α+β)+cosαsin(α+β)=1/3*1+0=1/3
