(1)sin(5π/6)=1/2
cos(5π/6)=-3的开方/2
tan(5π/6)=-3的开方/3
(2)sin(-2π/3)=-3的开方/2
cos(-2π/3)=-1/2
tan(-2π/3)=3的开方
(3)sin(-13π/6)=1/2
cos(-13π/6)=-3的开方/2
tan(-13π/6)=-3的开方/3