cosx+cos(120°-x)+cos(120°+x)
来源：学生作业帮助网 编辑：六六作业网 时间：2025/01/23 07:01:35
cosx+cos(120°-x)+cos(120°+x)cosx+cos(120°-x)+cos(120°+x)cosx+cos(120°-x)+cos(120°+x)cos(120°+x)=cos1
cosx+cos(120°-x)+cos(120°+x)
cosx+cos(120°-x)+cos(120°+x)
cosx+cos(120°-x)+cos(120°+x)
cos(120°+x)
=cos120°cosx-sin120°sinx
=-cos60°cosx-sin60°sinx
=-1/2 cosx-√3/2 sinx
同理,
cos(120°-x)=-1/2 cosx+√3/2 sinx
所以原式
=cosx-1/2 cosx-1/2 cosx
=0
cosx+cos(120°-x)+cos(120°+x)
为什么COS(-X)=COSX?
为什么cos（-x)=cosx.
cosX+cos（X+120°）+cos（X+240°）请问答案怎么求出为0 ,
求cosx+cos(120-x)+(120+x)的值快
f(x)=cos(x-120)-cosx的化简值
化简cosx-根号3cos(30°+x)+cos(x+60°)
化简cosx-√3 cos(30°+x)+cos(x+60°)
2cos(x+y)cosx-cos(2x+y)化简
COS(X+30°)=2/3 求COSX
cosx²等不等于cos²x?cosx²是cos（x)²还是（cosx)²?
cos(x+y)-cosx 等于多少?
化简1-cosx²/cos²x
化简1-cosx²/cos²x
cos根号下x如何变成cosx?
化简(tanx+cosx)cos^2x
cos(2π-x)=cosx吗如题
cosx^(2)和cos^2(x)区别