Congruences of quadrics in three-dimensional projective space associated with pair of surfaces
Two-parametric family (congruence) K<sub>2</sub> of quadrics Q in three-dimensional projective space P<sub>3</sub> is investigated, possessing the following properties: on each quadric there are two different focal points A<sub>1</sub> and A<sub>2</sub> at which focal tangents intersect at one point A<sub>0</sub> and are the asymptotic tangents of the surface (A<sub>0</sub>), and the tangents to the curves on the surface (A<sub>i</sub>) that corresponds the focal curves on the surface (A<sub>j</sub>) also intersect at one point A<sub>3</sub> and are the asymptotic tangents of the surface (A<sub>3</sub>), mareover the asymtotic curves that envelop A<sub>0</sub>A<sub>i</sub> and A<sub>3</sub>A<sub>j</sub> are correspond, and A<sub>0</sub> and A<sub>3</sub> are polar conjugated.