释义 |
Normal VectorThe normal to a Plane specified by
 | (1) |
is given by
 | (2) |
The normal vector at a point on a surface is
 | (3) |
In the Plane, the unit normal vector is defined by
 | (4) |
where is the unit Tangent Vector and is the polar angle. Given a unit Tangent Vector
 | (5) |
with , the normal is
 | (6) |
For a function given parametrically by , the normal vector relative to the point istherefore given by
To actually place the vector normal to the curve, it must be displaced by .
In 3-D Space, the unit normal is
 | (9) |
where is the Curvature. Given a 3-D surface ,
 | (10) |
If the surface is defined parametrically in the form
define the Vectors
 | (14) |
 | (15) |
Then the unit normal vector is
 | (16) |
Let be the discriminant of the Metric Tensor. Then
 | (17) |
See also Binormal Vector, Curvature, Frenet Formulas, Tangent Vector References
Gray, A. ``Tangent and Normal Lines to Plane Curves.'' §5.5 in Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 85-90, 1993. |