衡水原创黄金试卷高二数学答案

。sin 40(tan 10-tan 60)= sin 40(sin 10/cos 10-根号3) =sin40[(sin10-根号3)/cos10] = sin40。Cos10 =-1 2。tan 70 cos 10(tan 60 tan 20-1)= tan 70 cos 10(根号3s in 20/cos 20-1)= tan 70 cos 65438。...