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put this solution on YOUR website!Let s = the length of the side of the square, then the length of the diagonal is:

.
Using the Pythagorean relationship for the sides of a right triangle (

) in which c is the diagonal of the square, so:

and...

Expand the left side.

Subtract

from both sides.

Use the quadratic formula to solve:

where: a = -1, b = 4, and c = 4

or

Discard the negative (green) solution as the length of the side of a square is a positive value (red).

This is the exact value of the side of the square.

This is the approximate value.