If every positive number has two square roots and you can find of the side of a square window by finding a square root of the are, why is there only one answer for the length of a side?

Every positive number has two square roots - a positive and a negative (unless the value is 0).
The length of something can only be a positive number and since there is only one positive square root, there is only one answer.

Answer: r=4.5  feetexplanation: radius  r  is half of the diameter  d,⇒r=d2=92=4.5  feetidk i could be wrong

The answer would be a i think