First fundamental form
firstfirst quadratic forms
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product ofwikipedia
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Parametric surface
Curvature of parametric surfacesparameterizeparametric
be a parametric surface.
The curvature and arc length of curves on the surface, surface area, differential geometric invariants such as the first and second fundamental forms, Gaussian, mean, and principal curvatures can all be computed from a given parametrization.

Canonical form
canonicalnormal formcanonically
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of
In the study of manifolds in three dimensions, one has the first fundamental form, the second fundamental form and the third fundamental form.
Metric tensor
metricmetricsround metric
The first fundamental form is often written in the modern notation of the metric tensor.
is called the first fundamental form of M.
Curvature
curvednegative curvatureextrinsic curvature
. It permits the calculation of curvature and metric properties of a surface such as length and area in a manner consistent with the ambient space.
in terms of the coefficients of the first and second fundamental forms as
Second fundamental form
extrinsic curvaturesecondshape tensor
where L, M, and N are the coefficients of the second fundamental form.
Together with the first fundamental form, it serves to define extrinsic invariants of the surface, its principal curvatures.
Gaussian curvature
Gauss curvaturecurvatureLiebmann's theorem
The Gaussian curvature of a surface is given by
In fact, it can be found given the full knowledge of the first fundamental form and expressed via the first fundamental form and its partial derivatives of first and second order.

Line element
elements
The line element
Third fundamental form
The third fundamental form is expressible entirely in terms of the first fundamental form and second fundamental form.
Differential geometry
differentialdifferential geometerdifferential geometry and topology
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of
Inner product space
inner productinner-product spaceinner products
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of


Tangent space
tangent planetangenttangent vector
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of
Differential geometry of surfaces
surfaceshape operatorsmooth surface
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of









Euclidean space
EuclideanspaceEuclidean vector space
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of


Dot product
scalar productdotinner product
In differential geometry, the first fundamental form is the inner product on the tangent space of a surface in three-dimensional Euclidean space which is induced canonically from the dot product of

Ambient space
ambient
. It permits the calculation of curvature and metric properties of a surface such as length and area in a manner consistent with the ambient space.

Tangent vector
tangent vectorstangent directionstangent
Then the inner product of two tangent vectors is
Symmetric matrix
symmetricsymmetric matricessymmetrical
The first fundamental form may be represented as a symmetric matrix.
Lagrange's identity
can be expressed in terms of the first fundamental form with the assistance of Lagrange's identity,
Sphere
sphericalhemisphereglobose
The unit sphere in






Partial derivative
partial derivativespartial differentiationpartial differential
The coefficients of the first fundamental form may be found by taking the dot product of the partial derivatives.

Equator
equatorial plane0°The Equator
The equator of the sphere is a parametrized curve given by



Theorema Egregium
Theorema egregium of Gauss states that the Gaussian curvature of a surface can be expressed solely in terms of the first fundamental form and its derivatives, so that K is in fact an intrinsic invariant of the surface.


Carl Friedrich Gauss
GaussCarl GaussCarl Friedrich Gauß
Theorema egregium of Gauss states that the Gaussian curvature of a surface can be expressed solely in terms of the first fundamental form and its derivatives, so that K is in fact an intrinsic invariant of the surface.









Tautological one-form
canonical one-formCanonical symplectic formLiouville form