We know that a right triangle satisfies the pythagorean theorem:
![c^2=a^2+b^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/udh1dsx7kwgfauditnn86pp2qhoycm1tvv.png)
where a and b are the legs (the two smaller sides) and c is the hypotenuse.
To determine if the sides form a right triangle we plug the values into the pythagorean theorem, if the equation holds then the sides form a right triangle:
![\begin{gathered} 41^2=40^2+9^2 \\ 1681=1600+81 \\ 1681=1681 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/6w5jpizfmm0qh8fhyb5ux78y868nedttgi.png)
Since the equation holds we conclude that the sides given form a right triangle.