cos(-2040°) 等于多少
问题描述:
cos(-2040°) 等于多少
答
cos(-2040°)=cos(-6X360°+120°)=cos120°=cos(180°-60°)=-cos60°=-1/2
cos(-2040°) 等于多少
cos(-2040°)=cos(-6X360°+120°)=cos120°=cos(180°-60°)=-cos60°=-1/2