Unit and Principal Normal
- Author:
- Ryan Hirst
The line perpendicular to the tangent, and lying in the osculating plane (the plane through "three consecutive points" on the curve), is called the Principal Normal. For example, this curve lies completely in the plane (it's 2D), so the principal normal will always lie flat on the worksheet.
The Unit Normal may be chosen to face either direction along this line. Here are two ways we might choose :