Since the square is inscribed in the circle, a diagonal
of the square is a diameter of the circle.
The diameter of the circle = 2 x radius = 4 cm .
The diagonal of the square = 4 cm.
The diagonal of a square is (length of a side) x (√2).
Side x √2 = 4 cm
Divide each side by √2:
Side = 4 cm / √2 = 4 √2 / 2 = 2 √2 = 2.83 cm .