当k为任意整数时,化简 cos(2kπ-x)(-sin(2kπ-x))

问题描述:

当k为任意整数时,化简 cos(2kπ-x)(-sin(2kπ-x))

cos(2kπ-x)(-sin(2kπ-x))
=cos(-x)(-sin(-x))
=cos(x)sin(x)
=(1/2)sin(2x)不好意思,能不能再教我一题。假设 tan(x) = -8 并且 270o csc(x)=1/sinx=-(√65)/8