sina>√2/2
cosx≤1／2
画单位圆
找出上面两个范围的公共部分
sina>√2/2
2kπ+π/4＜x＜2kπ+3π/4
cosx≤1／2
2kπ+π/3≤x≤2kπ+5π/3
∴2kπ+π/3≤x＜2kπ+3π/4