The relationship between the side length of a square and the diameter of a circle that just fits inside it can be expressed as follows:
x = diameter of the circle / √2
Since the circumference of a circle is equal to π times the diameter, the circumference of the circle in terms of x can be found by solving for the diameter and then multiplying by π:
diameter of the circle = x * √2
circumference of the circle = π * diameter of the circle = π * (x * √2) = 2 * π * x * (1 / √2) = 2 * π * x * √2.
So, the exact circumference of the circle is 2 * π * x * √2 in terms of x