The curvature of a surface satisfies
where is the normal curvature in a direction making an angle with the first principal direction and and are the principal curvatures.
Euler Curvature Formula
See also
Principal CurvaturesExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Euler Curvature Formula." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/EulerCurvatureFormula.html