Question 301113
Let s = side of square.

Area = side^2

242 = side^2

sqrt{242} = side

We now use the Pythagorean Theorem.

[sqrt{242}]^2 + [sqrt{242}]^2 = d^2

Let d = diagonal.

242 + 242 = d^2

484 = d^2

sqrt{484} = sqrt{d^2}

22 = d

Your diagonal is 22.