Question

Решите пожааалуйста:
cos П/12 cos 7П/12-sin П/12 sin 7П/12=

Answer 1

cosπ/12 *cos7π/12-sinπ/12*sin7π/12=cos(π/12+7π/12)=cos8π/12=cos2π/3=-1/2=-0,5