cosa=1/3,且-π/2

问题描述:

cosa=1/3,且-π/2

cosa=1/3,且-π/2sina=-√(1-cos²a)=-2√2/3
[cot(-a-π)sin(2π+a)]/[cos(π+a)tan(3π-a)]
=(-cota*sina)/[(-cosa)*(-tana)]
=-cosa/sina
=√2/4