The side of the square is 1.5 cm (that is, all sides of the square are equal to 1.5 since they are equal).

The side of the square is 1.5 cm (that is, all sides of the square are equal to 1.5 since they are equal). We need to find the diagonal of the square.

The diagonal of a square can be considered as the hypotenuse of a triangle, where its sides are 1.5 cm long.
According to the Pythagorean theorem, the square of the hypotenuse is equal to the sum of the squares of the legs, that is
1.5 * 1.5 + 1.5 * 1.5 = 4.5.
The length of the hypotenuse is equal to the square root of 4.5, that is, 2.12 cm.