go off on a tangent
collocation突然离题；跑题
When she mentioned his ex, he went off on a tangent about his new job.
她一提到他的前任，他就开始跑题聊他的新工作。
正切（函数）；离题；跑题；视觉相切；击弦片；与曲线在一点相切而不交叉的直线
a line that touches a curve at only one point
与曲线在一点相切而不交叉的直线
A straight line touching a curve at a single point without crossing it there.
角的函数,给出正弦与余弦的比值,符号:tan, tg
A function of an angle that gives the ratio of the sine to the cosine, in either the real or complex numbers. Symbols: tan, tg.
与主要话题几乎无关但有共同点的话题
A topic nearly unrelated to the main topic, but having a point in common with it.
两条或多条线或边之间的视觉交互,常常是艺术家未预料到的关系
A visual interaction between two or more lines or edges that creates a perceived relationship between them, often in a way that the artist did not intend.
古钢琴中击打琴弦发声的小金属片
A small metal blade in a clavichord that strikes the strings to produce sound.
We were discussing the budget when she suddenly went off on a tangent about her vacation.
我们正在讨论预算，她突然跑题说起她的假期。
用法提示：tangent 为名词，在短语 go off on a tangent 中表示“跑题、偏离主题”。
His speech started well, but he kept going off on tangents that confused the audience.
他的演讲开头很好，但他一直跑题，让听众感到困惑。
用法提示：tangent 的复数形式 tangents 作介词宾语，指偏离主题的话题。
Please avoid tangents during the meeting so we can finish on time.
会议期间请避免跑题，这样我们才能按时结束。
用法提示：tangent 的复数形式作动词 avoid 的宾语，指偏离主题的内容。
比原词更正式，多用于书面或正式讲话，常指一段完整的离题内容。
指一句话或简短评论，不像原词可指一大段跑题内容；在戏剧中意为“旁白”。
用“绕路”比喻偏离，多指路线/计划/流程上的变通，语气比原词更具体，常跟 take 搭配。
取“与主要话题几乎无关但有共同点的话题”一义时，反义指谈话或文章实际围绕的中心话题；几何“切线”和三角“正切”义无反义。
与 go off on a tangent 相对的说法；指本应集中讨论的核心内容，常见于 get to the point 的对比。
突然离题；跑题
When she mentioned his ex, he went off on a tangent about his new job.
她一提到他的前任，他就开始跑题聊他的新工作。
切线
The tangent line touches the circle at exactly one point.
切线恰好与圆相交于一点。
正切函数
In trigonometry class, we learned to graph the tangent function.
三角函数课上，我们学习了绘制正切函数的图像。
tang- (触摸) + -ent (名词/形容词后缀：…者；…的)
tang- (触摸) + -ible (形容词后缀：可…的)
con- (共同) + -tact- (触摸) [tact 是 tangere 的过去分词词干]
in- (不) + -tact- (触碰) [tact 是 tangere 的过去分词词干]
切线是与曲线在一点相切且不穿过的直线。
正切是角的函数，表示该角的正弦与余弦之比。
正切的值等于正弦除以余弦，两者同属三角函数。
余弦是正切定义中的另一个三角函数，与正弦共同决定正切的比值。
在微积分中，函数在某点的导数等于该点切线的斜率。
突然岔开话题；偏离主题
We were discussing the budget when he went off on a tangent about his vacation.
我们正在讨论预算，他突然岔开话题说起他的假期。
突然转换话题；跑题
The speaker kept flying off at a tangent and never answered the question.
演讲者不停地跑题，始终没有回答问题。
Choose the next layer that will help you use tangent with more confidence.
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Preparing Usage patterns
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Preparing Common mistakes & Confusing words
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Dictionary facts from ECDICT, WIKTIONARY, WORDNET.