quadric : Idioms & Phrases
Principal axes of a quadric
(Geom.) , three lines in which the principal planes of the solid intersect two and two, as in an ellipsoid.
Webster 1913
Principal of a quadric
(Geom.) , three planes each of which is at right angles to the other two, and bisects all chords of the quadric perpendicular to the plane, as in an ellipsoid.
Webster 1913
quadric surface
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noun a curve or surface whose equation (in Cartesian coordinates) is of the second degree
quadric.