[sin330°-tan(-13π/3）]/[cos(-19π/6）-cos690°]

题目

[sin330°-tan(-13π/3）]/[cos(-19π/6）-cos690°]

答案

sin(330°）=sin(330-360)=-sin30°=-1/2tan(-13π/3)=-tan（13π/3)=-tan(4π+π/3)=-tan(π/3)=-根号3cos(-19π/6)=cos(19π/6)=cos(2π+π+π/6)=-cos(π/6)=-根号3/2cos690°=cos(720°-30°)=cos(-30°)=根号3/...