分类：教育/科学-学习帮助
问题：三角函数 
回答：解：原式=[(sin15-cos15)/cos15]/[(sin15+cos15)/cos15]
````````=(sin15-cos15)(sin15+cos15)/(sin15+cos15)²
````````=(sin²15-cos²15)/(1+2sin15cos15)
````````=-cos30/(1+sin30)
````````=-(√3/2)/(1+1/2)
````````=-√3/3