1590s, "meeting at a point without intersecting," from Latin tangentem (nominative tangens), present participle of tangere "to touch," from PIE root *tag- "to touch, to handle; border on; taste, partake of; strike, hit;" figuratively "affect, impress; trick, cheat; mention, speak of" (cognates: Latin tactus "touch;" Greek tassein "to arrange," tetagon "having seized;" Old English þaccian "stroke, strike gently"). First used by Danish mathematician Thomas Fincke in "Geomietria Rotundi" (1583). Extended sense of "slightly connected with a subject" is first recorded 1825. Related: Tangence; tangency.
tangent (n.)
1590s as a geometric function, from tangent (adj.). From 1650s as "a tangent line." Figurative use of off on a tangent is from 1771.
实用例句
1. The conversation went off at a tangent.
交谈突然偏离了正题。来自柯林斯例句
2. The graph of a concave function is always below its tangent.
一个凹函数的图象总在它的切线的下方.来自辞典例句
3. The tangent may be used to find the direction.
这方向也可用正切求得.来自辞典例句
4. For? 0 we naturally get a circle; for? 0 we obtain two tangent circles.
对? 0我们当然得到一个圆; 对? 0得到两个相切的圆.来自辞典例句
5. It's not easy to follow her thought because she's always going off at a tangent.
