（tan5π/4+tan5π/12）/（1－tan5π/12）=[tan(π+π/4)+tan5π/12]/(1-tan5π/12×tanπ/4)=(tanπ/4+tan5π/12)/[1-tan5π/12×tanπ/4]=tan(π/4+5π/12)=tan2π/3=-√3
