Given the triangle in the attached image.
We want to find the value of x.
Since the triangle is a right-angled triangle, we can apply the Pythagorean theorem to solve for the variable;

For the given triangle;

substituting the values;
![\begin{gathered} 18^2=x^2+x^2 \\ 18^2=2x^2 \\ x^2=(18^2)/(2) \\ x^2=(324)/(2) \\ x^2=162 \\ x=\sqrt[]{162} \\ x=9\sqrt[]{2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/nwmo6pr9vxc9vwdoqqo3hyupk9445xguph.png)
Therefore, the value of the variable x is;