(geometry几何) astraightlinethattouchestheoutsideofacurvebutdoesnotcrossit切线 (abbreviationtan) (mathematics数学) theratio of the length of the side opposite an angle in a right-angledtriangletothelengthofthesidenexttoit正切➡ comparecosine, sine●fly/gooffataˈtangent(BrE) (NAmEgooffonaˈtangent) (informal) tosuddenlystartsayingordoingsththatdoesnotseemtobeconnectedtowhathasgonebefore突然转换话题;突然改变行动