Question

三角函数 sin7/5pai*cos(-11/6pai)+tan(-15/4pai)*tan7/5pai

Answer 1

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/5)-tan(2π/5).

≈-2.254.