三角函数 sin7/5pai*cos(-11/6pai)+tan(-15/4pai)*tan7/5pai
问题描述：
三角函数 sin7/5pai*cos(-11/6pai)+tan(-15/4pai)*tan7/5pai
答
化简三角函数：原式=sin(π+2π/5)*cos[-(π+5π/6)]+tan[-(4π+π/4)]*tan(π+2/5π). =-sin(2π/5)cos(5π/6)-tan(π/4)*tan(2π/5). =-sin(2π/5)*[-cos(π/6)]-1*tan(2π/5). =(√3/2)sin(2π...