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

Because the 2 square roots are positive and negative
ex
squareroot of 4=2 or -2 since 2 time2=4 and -2 times -2=4
we normally use the principal root or the positive root since legnth in real life cannot be negative

you cannot have a window that is -5 inches long

th enaswe ris because one s negative and cannot be used