cos2分之19π等于什么?
问题描述：
cos2分之19π等于什么?
答
cos（8π+3/2π）
=cos（3/2π）=0
答
答：
cos2分之19π
=cos(19π/2)
=cos(10π-π/2)
=cos(-π/2)
=0
答
解
cos(19π/2)
=cos(10π-π/2)
=cos(-π/2)
=cosπ/2
=0
答
cos(2分之19π)
= cos(8π + 3π/2)
= cos(3π/2)
= 0