A complete quadrilateral is the figure determined by four lines, no three of which
are concurrent, and their six points of intersection. Figure 1 shows a complete
quadrilateral ABCDEF, with its three diagonals AC, BD, and EF (compared
to two for an ordinary quadrilateral). The midpoints M, N, L of these diagonals
are collinear on a line, called the Newton-Gauss line of the complete quadrilateral
([1, pp.152–153]). In this note, we present some properties of the Newton - Gauss
lines of complete quadrilaterals associated with a cyclic quadrilateral.