tangent <differential geometry, calculus>
direction indicating the instantaneous direction of a curve at a point
Note to entry: The tangent is usually calculated by differentiation of a functional representation of a curve but it may be approximated by a secant (double intersection) line from the point passing through another nearby point on the curve. The closer the second point is to the first, the better the approximation of the tangent's direction.
ORIGIN: ISO/TC 211 Glossary of Terms - English (last updated: 2020-06-02)