Let be a Regular Surface and a unit Tangent Vector to , and let be the Plane determined by and the normal to the surface . Then the normal section of is defined as the intersection of and .

**References**

Gray, A. *Modern Differential Geometry of Curves and Surfaces.* Boca Raton, FL: CRC Press, p. 271, 1993.

© 1996-9

1999-05-25