作业帮已知sin(α+π/12)＝1/3,求cos(α+7π/12)的值
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/29 12:20:49
已知sin(α+π/12)＝1/3,求cos(α+7π/12)的值
已知sin(α+π/12)＝1/3,求cos(α+7π/12)的值
已知sin(α+π/12)＝1/3,求cos(α+7π/12)的值
cos(α+7π/12)
=sin(-α+-π/12)
=-sin(α+π/12)
=-1/3
cos(α+7π/12)=cos(α+π/12+π/2)=cos(α+π/12)cos(π/2)-sin(α+π/12)sin(π/2)=-sin(α+π/12)