1. In geometry and physics, the direction perpendicular to a surface or plane at a given point
The normal direction to the surface points outward from the sphere.
A direção normal à superfície aponta para fora da esfera.
2. In mathematics, a vector or line that is perpendicular to a curve or surface
Calculate the normal direction at each point on the curve.
Calcule a direção normal em cada ponto da curva.