Binormal Vector

Definition

$\mathbf{B}=\mathbf{T}\times \mathbf{N}$

Cross Product of Unit Tangent Vector $\mathbf{T}$ and Principal Unit Normal Vector $\mathbf{N}$

Facts

$\frac{d\mathbf{B}}{ds}=-\tau N$ where $\tau$ is the Torsion of Curves

$\frac{d\mathbf{B}}{ds}=\mathbf{T}\times \frac{d\mathbf{N}}{ds}$