利用和(差)角公式求下列各三角函数的值sin(-7π/12)

问题描述:

利用和(差)角公式求下列各三角函数的值
sin(-7π/12)

满意答案错了吧 ?-sin(π/3+π/4)=-[sinπ/3cosπ/4+cosπ/3isnπ/4]

sin(-7π/12)=sin(-π/3-π/4)=sin(-π/3)cos(-π/3)-cos(π/4)sin(π/4)