Answer:
The correct option is:
[tex]10\sqrt{2}[/tex]
Explanation:
A square has all of its sides of the same length. With two sides and a diagonal, we can create the right traingle:
Where L is the length of the side of the square.
By the pythagorean theorem:
[tex]20^2=L^2+L^2[/tex]
And solve for L:
[tex]\begin{gathered} 20^2=L^2+L^2 \\ 400=2L^2 \\ \frac{400}{2}=L^2 \\ \sqrt{200}=L \\ L=10\sqrt{2} \end{gathered}[/tex]
