cos(X+t)-cosX化简
答案:2 悬赏:20 手机版
解决时间 2021-01-26 19:35
- 提问者网友：回忆在搜索
- 2021-01-26 02:31
cos(X+t)-cosX化简
最佳答案
- 五星知识达人网友：毛毛
- 2021-01-26 02:38
cos(X+t)-cosX
=cos(X+t/2+t/2)-cos(X+t/2-t/2)
=-2sin(X+t/2)sin(t/2)
=cos(X+t/2+t/2)-cos(X+t/2-t/2)
=-2sin(X+t/2)sin(t/2)
全部回答
- 1楼网友：你哪知我潦倒为你
- 2021-01-26 04:04
sin(x+t)-sinx=sin(x+t/2+t/2)-sin(x+t/2-t/2)
=sin(x+t/2)*cost/2+cos(x+t/2)*sint/2-[sin(x+t/2)*cost/2-cos(x+t/2)*sint/2]
=2sint/2*cos(x+t/2)
所以2sint/2*cos(x+t/2)=sin(x+t)-sinx=-t
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