Since quadrilaterals ABCD and LMNO are congruent to STUV, which is a rectangle, we can conclude the following about the diagonals.
In a rectangle, the diagonals are equal in length. Therefore, the length of diagonal \( SU \) in rectangle \( STUV \) is 5 cm. By the property of congruence:
- Since \( ABCD \cong STUV \), the lengths of the corresponding diagonals \( AC \) and \( BD \) in quadrilateral \( ABCD \) must also be equal to the length of the diagonals in rectangle \( STUV \).
Thus, by the Transitive Property, we can state:
\[ AC = BD = SU = 5 \text{ cm} \]
So, the lengths of diagonals \( AC \) and \( BD \) are both 5 cm.