计算tanπ/12的值
问题描述：
计算tanπ/12的值
答
tan(π/12)
=sin(π/12)/cos(π/12)
=2sin²(π/12)/[2sin(π/12)*cos(π/12)]
=[1-cos(π/6)]/sin(π/6)
=(1-√3/2)/(1/2)
=2-√3