cos三分之二派等于多少
问题描述：
cos三分之二派等于多少
答
cos(2π/3)=cos120°＝－1/2
答
cos三分之二派
=cos(π/6+π/2)
=-sinπ/6
=-1/2
答
答：
cos(2π/3)
=cos(π-π/3)
=-cosπ/3
=-1/2