---
tag: 0ZCZK72B45
kind: concept
name: Tangent vector of a curve
aliases: [velocity-vector]
msc: [53A04]
uses: [0G7WM8DX4P]
sources:
  - url: https://en.wikipedia.org/wiki/Differentiable_curve
    locator: Tangent vector
---

## Summary

The tangent vector of a differentiable [[parametrised curve|0G7WM8DX4P]] at a parameter value is the derivative of the curve there.
If the curve is the path of a moving point, the tangent vector is its velocity, and its length is the speed.