sin(7兀/6)=sin(兀+1兀/6)=-sin(1兀/6)=-1/2
cos(7兀/6)=con(兀+1兀/6)=-con(1兀/6)=-√3/2
tan(7兀/6)=tan(兀+1兀/6)=tan(1兀/6)=√3/3
sin(π+α)= -sinα
cos(π+α)= -cosα
tan(π+α)= tanα
因为7pai/6=(pai+pai/6) 所以sin(7pai/6)=-sin(pai/6)=-1/2 cos(7pai/6)=-cos(pai/6)=-(根号3)/2 tan(7pai/6)=tan(pai/6)=(根号3)/2