Final answer:
The side length of the square is approximately √148 cm.
Step-by-step explanation:
To find the length of the side of the square with the same diagonal as the rectangle, we can use the Pythagorean theorem. The diagonal of the rectangle can be found using the formula √(length^2 + width^2). Substituting the values from the rectangle with sides 12 cm and 2 cm, we get √(12^2 + 2^2) = √(144 + 4) = √148. The side length of the square is equal to the diagonal, so the side length of the square is approximately √148 cm.