Vector which is perpendicular to said surface or manifold. In a inner product space, the inner product of the normal vector with all vectors which comprise the surface is 0.
... are held in St. Louis, Missouri, USA
Births:
January 5 - Jeane Dixon[?], astrologer (+ 1997)
January 10 - Ray Bolger, actor, singer, dancer (+ 1987)
January 18 ...