Theorema Egregium

In differential geometry, the Theorema Egregium ('Remarkable Theorem'), is an important theorem of Carl Friedrich Gauss discovered in 1828 and concerning the Gaussian curvature of surfaces. Informally, the theorem says that the curvature of a surface can be determined entirely by measuring angles and distances on the surface, that is, it does not depend on how the surface might be embedded in (3-dimensional) space. In other words the Gaussian curvature is intrinsic.
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