SOLUTION
Consider the figure below
The diagonal of the square is shown
Using Pythagoras theorem, it follows:
[tex]d^2=x^2+x^2[/tex]
Solve the equation for d
[tex]\begin{gathered} d^2=2x^2 \\ d=\sqrt[]{2x^2} \\ d=x\sqrt[]{2} \end{gathered}[/tex]
Therefore the diagonal of the square is
[tex]d=x\sqrt[]{2}[/tex]
