Relating Sides of a Triangle

What is the length ‘y‘ expressed in terms of ‘x‘?

Rendered by QuickLaTeX.com

    \begin{equation*}     a^2 + b^2 = c^2 \end{equation*}

    \begin{equation*}     x^2 + x^2 = \left( \frac{y}{3} \right)^2 \end{equation*}

    \begin{equation*}     \sqrt{2 x^2} = \sqrt{\left( \frac{y}{3} \right)^2} \end{equation*}

    \begin{equation*}     x \sqrt{2} = \frac{y}{3} \end{equation*}

    \begin{equation*}     3 \left( x \sqrt{2} \right) = \left( \frac{y}{3} \right) 3 \end{equation*}

    \begin{equation*}     \boxed{3 x \sqrt{2} = y} \end{equation*}