Answer:
Yes, 9^2+40^2=41^2
Explanation:
From the Pythagoras’ theorem, the square of the hypotenuse of a right triangle equals the sum of the squares of the two other sides 
From what we have , the side lengths are 9, 40 and 41 
As we can see, 41 is the longest side length and that makes it the hypotenuse 
The square of the two other sides is 40^2 + 9^2 = 1,681
Also, 41^2 = 1,681
As we can see, the sum of the squares equal the square of the hypotenuse 
Since this follows the theorem, we can conclude that the triangle is a right triangle