Question

（tan10-根号3）乘sin40=？

求解答过程，在线等待

Answer 1

解答：
(tan10-根号3）*sin40=(sin10/cos10-根号3)*sin40=[(sin10-根号3cos10)/cos10]*sin40
=[2sin(10-60)/cos10]*sin40=(-2sin40cos40)/cos10=-sin80/cos10
=-cos10/cos10=-1

Answer 2

=(sin10/cos10-sin60/cos60)*sin40
=sin40*(sin10cos60-sin60cos10)/(cos10cos60)
=-sin40sin50/(cos10cos60)
=-sin40cos40/(cos10cos60)
=-1/2*sin80/(sin80cos60)
=-1/2/(1/2)
=-1