Find the length of the diagonal of a square with an area of 20 cm².

So, if we know that the area of a square is 20 square units, then according to a special rule we can find how much one side is.

According to the properties of a square, one side will then be √20.

Further, in solving the problem, we will again need the properties of the square.

So, if we know the side, then we can find the area.

According to the properties of the square, it is found as follows:

√20 in the second degree + √20 in the second degree. It turns out 40.

And in the final result, we get that the diagonal is equal to √40.