[tex]\bf \textit{using the pythagorean theorem}\\\\
c^2=a^2+b^2\implies c=\sqrt{a^2+b^2}\qquad
\begin{cases}
c=hypotenuse=x\\
a=adjacent=12\\
b=opposite=12\\
\end{cases}
\\\\\\
x=\sqrt{12^2+12^2}\implies x=\sqrt{288}\implies x=\sqrt{12^2\cdot 2}
\\\\\\
x=12\sqrt{2}[/tex]
