不看根号=1+tan²(-π/6-6π)-2tan(-π/6-7π)=1+tan²(-π/6)-2tan(-π/6)tan(-π/6)=-tanπ/6=-√3/3所以=1+1/3+2√3/3=(4+2√3)/3=(√3+1)²/3原式=(√3+1)/√3=(3+√3)/3
