tan(x)=sin(x pi/2) sin(x)等于多少一楼正确

tan(x)=sin(x pi/2) sin(x)等于多少一楼正确
tan(x)=sin(x pi/2) sin(x)等于多少
一楼正确

tan(x)=sin(x pi/2) sin(x)等于多少一楼正确
化为 sin(x)/cos(x)=-cos(x)
则sin(x)=-cos²(x)
即0=sin²(x)-sin(x)-1
设sin(x)=a 即 a²-a-1=0
a=(1±√5)/2
又 (1+√5)/2 >1
显然不满足条件
∴sinx=(1-√5)/2