Congruences of quadrics in three-dimensional projective space associated with pair of surfaces
Two-parametric family (congruence) K2 of quadrics Q in three-dimensional projective space P3 is investigated, possessing the following properties: on each quadric there are two different focal points A1 and A2 at which focal tangents intersect at one point A0 and are the asymptotic tangents of the surface (A0), and the tangents to the curves on the surface (Ai) that corresponds the focal curves on the surface (Aj) also intersect at one point A3 and are the asymptotic tangents of the surface (A3), mareover the asymtotic curves that envelop A0Ai and A3Aj are correspond, and A0 and A3 are polar conjugated.