原式=cos5π/4+tanπ/6
=-cosπ/4+tanπ/6
=-(根号2)/2+(根号3)/3哪里不懂请问，没问题请采纳~~~~~~~~~~~~~~原式=cos5π/4+tanπ/6这个哪里来的？诱导公式cosx=cos(x+2π)tanx=tan(x+2π)cosx=-cos(x+π)还是不懂，具体可以写出来吗？cos13π/4+tan(-11π/6)=cos(13π/4-2π)+tan(-11π/6+2π)这些变换都是根据诱导公式来做的，诱导公式是需要背的=cos(5π/4)+tan(π/4)=-cos(5π/4-π)+tan(π/4)=-cosπ/4+tanπ/4=-(根号2)/2+(根号3)/3哪里不懂请问，没问题请采纳~~~~~~~~~~~~~~