Question

tanx大于等于-1 sinx>-1/2且cosx>1/2求x的集合.

Answer 1

tanx>=-1,得：x为[kπ-π/4,kπ+π/2)

sinx>-1/2,得：x为(2kπ-π/6,2kπ+7π/6)

cosx>1/2,得：x为(2kπ-π/3,2kπ+π/3)

以上集合的交集即为解x的集合：

(2kπ-π/6,2kπ+π/3),k为任意整数