sin(x-27°)cos(18°-x)-sin(60°-x)sin(x-18°)
问题描述：
sin(x-27°)cos(18°-x)-sin(60°-x)sin(x-18°)
为啥答案给的可以化简为sin(x+27°)cos(18°-x)+cos(90°-63°+x)sin(18°-x)
答
sin(x-27°)cos(18°-x)-sin(【63°】-x)sin(x-18°)
=sin(x+27°)cos(18°-x)+cos(90°-【63°-x】)sin(18°-x)
=sin(x+27°)cos(18°-x)+cos(90°-63°+x)sin(18°-x)
=sin(x+27°)cos(18°-x)+cos(27°+x)sin(18°-x)
=sin45°
=√2/2不好意思追问一下哈 那个sin（x-27°）为啥可以直接划成sin（x+27°）？不好意思追问一下哈 那个sin（x-27°）为啥可以直接划成sin（x+27°）？没有注意，应该是我抄写错了！
sin(x-27°)cos(18°-x)-sin(【63】°-x)sin(x-18°)
=cos(90-（x-27°）)cos(18°-x)-sin(【63】°-x)sin(x-18°)
=cos(63°-x）)cos(18°-x)-sin(【63】°-x)sin(x-18°)
=cos【（63°-x)+(x-18°)】
=cos45°