作业帮若(cos2x)/[sin(x-π/4)]=（-根号2）/2,则cosx+sinx=?
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/05 11:50:46
![若(cos2x)/[sin(x-π/4)]=（-根号2）/2,则cosx+sinx=?](/uploads/image/z/351208-64-8.jpg?t=%E8%8B%A5%28cos2x%29%2F%5Bsin%28x-%CF%80%2F4%29%5D%3D%EF%BC%88-%E6%A0%B9%E5%8F%B72%EF%BC%89%2F2%2C%E5%88%99cosx%2Bsinx%3D%3F)
若(cos2x)/[sin(x-π/4)]=（-根号2）/2,则cosx+sinx=?
若(cos2x)/[sin(x-π/4)]=（-根号2）/2,则cosx+sinx=?
若(cos2x)/[sin(x-π/4)]=（-根号2）/2,则cosx+sinx=?
(cos2x)/[sin(x-π/4)]
=[(cosx)^2-(sinx)^2]/[((根号2)/2)sinx-((根号2)/2)cosx]
=(cosx-sinx)(cosx+sinx)/[-((根号2)/2)(cosx-sinx)]
=(cosx+sinx)/[-(根号2)/2]=-(根号2)/2,
所以 sinx+cosx= 1/2.