sin(α+π/6)=1/3sin[π-(α+π/6)]=1/3sin(5/6π-α)=1/3sin²(5/6π-α)=1/9cos²(5/6π-α)=1-sin²(5/6π-α)=8/9tan²(5/6π-α)=sin²(5/6π-α)/cos²(5/6π-α)=1/9 / 8/9=1/8