Planar Point
A point p on a Regular Surface 
is said to be planar if the Gaussian Curvature
and 
(where 
is the Shape Operator), or equivalently, both of the Principal Curvatures 
and 
are 0.
References
Gray, A. Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, p. 280, 1993.
- Hoof
- Hook
- Hook Length Formula
- Hopf Algebra
- Hopf Bifurcation
- Hopf Circle
- Hopf Link
- Hopf Map
- Hopf's Theorem
- Horizontal
- Horizontal-Vertical Illusion
- Horn Angle
- Horn Cyclide
- Horned Sphere
- Horner's Method
- Horner's Rule
- Horn Torus
- Horocycle
- Horse Fetter
- Horseshoe Map
- Hough Transform
- Householder's Method
- Howell Design
- H-Spread
- H-Transform