求三角函数sin(-31π/4)=?cos(-1182°13′)
问题描述:
求三角函数sin(-31π/4)=?cos(-1182°13′)
答
sin(-31π/4)
=sin(-4×2π+π/4)
=sin(π/4)
=√2/2
cos(-1182°13′)
=cos(-3×360-102°13′)
=cos(102°13′)
=cos(180-77°47′)
=-cos(77°47′)
约等于-0.2116