Given a right angled triangle, we shall solve for the unknown side by applying the Pythagoras' theorem which is;

Where c is the hypotenuse (side facing the right angle) and then a and b are the other two sides.
Substituting for the given values, we shall now have the following;

Take the square root of both sides;
![\begin{gathered} \sqrt[]{c^2}=\sqrt[]{50} \\ c=\sqrt[]{50} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/l9biw7m5hi2wp85u54yq0sigcms2ea0ext.png)
We can now re-arrange the the right side of the equation;
![\begin{gathered} c=\sqrt[]{2*25} \\ c=\sqrt[]{2}*\sqrt[]{25} \\ c=5\sqrt[]{2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/lejoof6acb0gdvrzncj9nstjh40d7orh35.png)
ANSWER:
The third side of the triangle would now be;
![5\sqrt[]{2}](https://img.qammunity.org/2023/formulas/mathematics/college/8xvjn403qdbo7h1xksfr3a0v3r28mex0r3.png)