a straight line or plane that touches a curve or curved surface at a point but does not intersect it at that point
ratio of the opposite to the adjacent side of a right-angled triangle
tangent的用法和樣例：
例句
用作形容詞 (adj.)
Some examples are given by inscribed and circumscribed circles ofpolygons, lines intersecting and tangent toconic sections, thePappusandMenelausconfigurations of points and lines. 一些例子所給予者和限制各界的多邊形，線相交和相切的圓錐部分，帕普斯和墨涅拉俄斯配置的點和線。
用作名詞 (n.)
The graph of a concave function is always below its tangent. 一個凹函數的圖象總在它的切線的下方。
Both of approaching and returning movements are along the tangent of the circle. 繞轉之後移動方向為自南向北，也是沿圓周的切線運動。
The tangent may be used to find the direction. 這方向也可用正切求得。
Store normals in generic space, e.g., Tangent Space. 存儲非普通空間的法向量，例如，正切空間。
