Quadrilateral A'B'C'D'A ′ B ′ C ′ D ′ A, prime, B, prime, C, prime, D, prime is the image of quadrilateral ABCDABCDA, B, C, D under a dilation with a scale factor of \dfrac{1}{3} 3 1 start fraction, 1, divided by, 3, end fraction.What is the length of segment \overline{CD} CD start overline, C, D, end overline?