(1)[π/4+2kπ,3π/4+2kπ] k属于整数
(2)[-π/2+2kπ,-π/3+2kπ] 和[π/3+2kπ,3π/2+2kπ] k属于整数
(3)[-π/4+kπ,π/2+kπ) k属于整数
(4)(-π/6+2Kπ,π/3+2kπ) K属于整数
先画出相应的三角函数图象
(1)[π/4+2kπ,3π/4+2kπ] k属于整数
(2)[-π/2+2kπ,-π/3+2kπ] 和[π/3+2kπ,3π/2+2kπ] k属于整数
(3)[-π/4+kπ,π/2+kπ) k属于整数
(4)(-π/6+2Kπ,π/3+2kπ) K属于整数
先画出相应的三角函数图象