tanπ/12-cotπ/12

tanπ/12-cotπ/12
tanπ/12-cotπ/12

tanπ/12-cotπ/12
=sinπ/12/cosπ/12-cosπ/12/sinπ/12
=(sin²π/12-cos²π/12)/(sinπ/12cosπ/12)
=-cos(2*π/12)/[1/2*sin(2*π/12)]
=-cosπ/6/(1/2*sinπ/6)
=-2√3