<image>(Autumn 2015, Midterm Examination in Binhu District) As shown in the figure, in quadrilateral ABCD, AD ∥ BC, ∠B = 90°, AB = AD = 4 cm, and BC = 7 cm. Now, a paper in the shape of quadrilateral ABCD is to be cut to obtain an isosceles triangle with leg length of 3 cm (Requirements: One vertex of the isosceles triangle coincides with one vertex of quadrilateral ABCD, and the other two vertices lie on the sides of quadrilateral ABCD). Then, there are ____ possible values for the length of the base of the cut isosceles triangle.