In this paper, we obtain some relations related to the principal sectional curvatures of generalized semi ruled surfaces with central ruled surfaces in terms of the determinant of the first fundamental form of these surfaces. Also, we investigate the same relations at the central points of generalized semi ruled surfaces. Moreover by applying Euler theorem to tangential sections of the generalized semi ruled surfaces in n-dimensional semi Euclidean space. We find the relationship between the sectional curvatures of non-degenerate sections and the principal sections in two different type and call as 1 st and 2 nd type Semi Euclidean Beltrami-Euler formulas.