要的,接下来要做的就是求[kπ-π/12,kπ+5π/12]与[π/4,π/2]的交集；从0的左边开始尝试；k=-1时,[kπ-π/12,kπ+5π/12]是一个负区间,显然与[π/4,π/2]无交集,舍去；k=0时,[kπ-π/12,kπ+5π/12]=[-π/12,5π/12...