化简三角函数[sin(α+pi)*cos(pi+α)*cos(α+2pi)]/[tan(pi+α)*cos^3(-α-pi)][s_数学解答

化简三角函数[sin(α+pi)*cos(pi+α)*cos(α+2pi)]/[tan(pi+α)*cos^3(-α-pi)]
[sin(α+pi)*cos(pi+α)*cos(α+2pi)]/[tan(pi+α)*cos^3(-α-pi)]
算出来最后等于1 ,

人气：465 ℃　时间：2020-03-25 22:07:09

解答

[sin(α+pi)*cos(pi+α)*cos(α+2pi)]/[tan(pi+α)*cos^3(-α-pi)]
=[(-sin(α))*(-cos(α))*cos(α)]/[tan(α)*(-cos^3(α))]
=-sinα*cosα*cosα*cosα/sinα*cosα*cosα*cosα
=-1
应该是-1