This document discusses arc length and the unit tangent vector T for a curve, as well as torsion and the unit binormal vector B. It introduces the Frenet frame or TNB frame, which uses the unit tangent, normal, and binormal vectors to describe a curve.

2. Arc Length and
Unit Tangent Vector T
Chapter 13

3. Arc Length

10. Torsion and the Unit Binormal Vector B
FRENET FRAME OR TNB FRAME

20. Torsion