In a parallelogram, opposite sides are equal in length. Since you have the lengths of sides BC and CD, we can determine the lengths of sides AB and AD.
- You have BC = 7 cm. Therefore, AB (which is opposite to BC) is also 7 cm.
- You have CD = 5 cm. Therefore, AD (which is opposite to CD) is also 5 cm.
Thus, the length of AB is 7 cm.
Response: 7 cm