In algebraic geometry, given a projective algebraic hypersurface described by the homogeneous equation

and a point

its polar hypersurface is the hypersurface

where are the partial derivatives of .

The intersection of and is the set of points such that the tangent at to meets .

• Dolgachev, Igor V. (2012-08-16). Classical Algebraic Geometry: A Modern View (PDF) (1 ed.). Cambridge University Press. doi:10.1017/cbo9781139084437. ISBN 978-1-107-01765-8.