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be tangential to sth
几何中表示“与……相切”；也可引申指与主题关联不大。
The line is tangential to the circle at point P.
这条线在P点与圆相切。
切线的；相切的；正切的
先理解核心含义，再看它在真实句子里的用法。
切线的；相切的；正切的
of, relating to, or acting along a tangent line
The line is tangential to the circle at point P.
这条线在P点与圆相切。
切线的；沿切线方向运动的
Referring to a tangent, moving at a tangent to something.
仅接触的,处于切线位置的。
Merely touching, positioned as a tangent.
仅间接相关的
Only indirectly related.
Draw a line tangential to the circle at point A.
在A点画一条与圆相切的直线。
The car only made tangential contact with the fence, so there was almost no damage.
汽车只与栅栏发生擦碰，所以几乎没有损坏。
The stone flies off the spinning wheel in a tangential direction.
石头沿切向方向飞离旋转的轮子。
几何中表示“与……相切”；也可引申指与主题关联不大。
The line is tangential to the circle at point P.
这条线在P点与圆相切。
形容词作定语，常修饰comment、remark、issue、point等，表示“离题的、关联不大的”。
She made a tangential remark about the weather.
她关于天气说了一句题外话。
Not this
His remarks were a tangent to the main issue.
Use this
His remarks were tangential to the main issue.
表示“离题的、不直接相关的”时，tangential 是形容词，应直接作表语；而 tangent 是名词，常用于 go off on a tangent 中，不能说 His remarks were a tangent。因此把 a tangent 改为 tangential。
Not this
Her question was tangential with the main topic.
Use this
Her question was tangential to the main topic.
表达“与……只有少许关联、离题”时，tangential 后接介词 to，构成固定搭配 tangential to something；受中文“与……相切/相关”的影响，容易误用 with。只需把 with 改为 to 即可。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
切线方向
The car moves in a tangential direction when it leaves the curve.
汽车离开弯道时沿切线方向行驶。
切向速度
The tangential velocity of the satellite depends on its orbit.
卫星的切向速度取决于其轨道。
切向力
A tangential force can cause an object to accelerate along its path.
切向力能使物体沿其路径加速。
离题的评论
The professor ignored the student's tangential remark and continued the lecture.
教授忽略了学生的离题评论，继续讲课。
离题的问题
We should not spend too much time on tangential issues during the meeting.
会议期间我们不应在离题的问题上花太多时间。
与主题偏离的；离题的
Our discussion became tangential to the topic, so we returned to the main argument.
我们的讨论变得离题，于是我们回到了主要的观点。
Use tangential naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
tangential 以 tangent（切线）开头，切线擦圆即飞远：既记“切线的”，也记“离题的”。
语域：formal 常见场景：数学与几何教材或课堂、学术论文、评论及正式演讲 该词通常较正式：几何语境中指“切线的、相切的”，多用于数学、物理等专业文本；在学术或评论语境中引申为“离题的、仅略微相关”，多用于书面表达。
这些词都包含 -ential，重读音节里有相同的 /enʃəl/，与 tangential 的重读部分 /dʒenʃəl/ 押韵。注意 tangent /ˈtændʒənt/ 和 tangible /ˈtændʒəbəl/ 虽然拼写相近，但发音不同，不押韵。
Dictionary facts from ECDICT, WIKTIONARY.