Answer:
Exact: 2sqrt(5)
Approximate: 4.472
Step-by-step explanation:
The side of the square is the hypotenuse of a right triangle with legs of lengths 2 and 4.
c^2 = a^2 + b^2
c^2 = 2^2 + 4^2
c^2 = 4 + 16
c^2 = 20
c = sqrt(20)
c = sqrt(4 * 5)
c = 2sqrt(5) = 4.472
