已知角的终边经过点P(sin5π/6,cos5π/6),则角可能是（ ）.A.-π/3 B.π/3 C.π/6 D.5π/6
问题描述：
已知角的终边经过点P(sin5π/6,cos5π/6),则角可能是（ ）.
A.-π/3 B.π/3 C.π/6 D.5π/6
答
tana=y/x=cos5π/6/sin5π/6=cot5π/6=cot(π-π/6)=-cotπ/6=-tan(π/2-π/6)=-tan(π/3)=tan(-π/3)
所以选A