高二数学,划线第一步怎么弄成第二步的
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/08/30 09:54:25
高二数学,划线第一步怎么弄成第二步的
和差化积
sinx+siny=2sin[(x+y)/2]cos[(x-y)/2]
sinx-siny=2cos[(x+y)/2]sin[(x-y)/2]
cosx+cosy=2cos[(x+y)/2]cos[(x-y)/2]
cosx-cosy=-2sin[(x+y)/2]sin[(x-y)/2]
积化和差
sinxsiny=-1/2[cos(x+y)-cos(x-y)]
cosxcosy=1/2[cos(x+y)+cos(x-y)]
sinxcosy=1/2[sin(x+y)+sin(x-y)]
cosxsiny=1/2[sin(x+y)-sin(x-y)]
再问: 谢谢,你能在这里用一下我看看吗?
sinx+siny=2sin[(x+y)/2]cos[(x-y)/2]
sinx-siny=2cos[(x+y)/2]sin[(x-y)/2]
cosx+cosy=2cos[(x+y)/2]cos[(x-y)/2]
cosx-cosy=-2sin[(x+y)/2]sin[(x-y)/2]
积化和差
sinxsiny=-1/2[cos(x+y)-cos(x-y)]
cosxcosy=1/2[cos(x+y)+cos(x-y)]
sinxcosy=1/2[sin(x+y)+sin(x-y)]
cosxsiny=1/2[sin(x+y)-sin(x-y)]
再问: 谢谢,你能在这里用一下我看看吗?