已知sin(7/12π+α)=2/3,求cos(α-11/12π)的值 谢谢老师回答
问题描述:
已知sin(7/12π+α)=2/3,求cos(α-11/12π)的值 谢谢老师回答
答
sin(7/12π+α)=2/3
α=arcsin(2/3)-7/12π
cos(α-11/12π)
=cos(arcsin(2/3)-7/12π-11/12π)
=cos(arcsin(2/3)-18/12π)
=cos(arcsin(2/3)-3/2π)
=-2/3