Answer:
28.3 cm
Step-by-step explanation:
Let x represent the length of one side of the square. Then, by the Pythagorean Theorem,
x^2 + x^2 = (40 cm)^2, or
2x^2 = 1600 cm^2.
Thus, x^2 = 800 cm2, and x, the length of one side, is √800, or 28.3 cm to the nearest tenth of a cm.
