It's important to know that the converse of the Pythagorean Theorem states that if the square of the length of the longest side of a triangle is equal to the sum of the squares of the other two sides, then the triangle is a right triangle.
Let's apply the converse to the given triangle.
[tex]\begin{gathered} 6^2=4^2+5^2 \\ 36=16+25 \\ 36=41 \end{gathered}[/tex]
As you can observe, this result is false because 36 is not equal to 36.
Therefore, by the converse of the Pythagorean Theorem, the triangle is not a right triangle.
