ANSWER
These three side lengths do form a right triangle.
Step-by-step explanation
If the side lengths satisfy the Pythagorean theorem, then they form a right triangle.
The hypotenuse is always the longest side:
![\begin{gathered} 65^2=16^2+63^2 \\ 4225=256+3969 \\ 4225=4225\text{ }\rightarrow\text{ true} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/bvjjv9m35iopjccsiq53atsafmza0esihp.png)
These side lengths satisfy the Pythagorean theorem, therefore they form a right triangle.