tanα+tanβ=-4tanαtanβ=-3tan(α+β)=-4/(1+3)=-1sin^2（α+β）+sin(α+β)cos(α+β)=[sin^2（α+β）+sin(α+β)cos(α+β)]/1=[sin^2（α+β）+sin(α+β)cos(α+β)]/[sin^2（α+β）+cos^2(α+β)]=[tan^2(...