Which of the following sets could be the sides of a right triangle?
a. {2, 3,√10 }
b. {3, 5, √34}
c. {5, 8, 12}

For this we need to test each set of sides for Pythagoras theorem.
If square for longest side is equal to sum of squares of shorter sides than that triangle is right.

For B we have:
(√34)^2 = 3^2 + 5^2

34 = 9 + 25

as we can see this set of sides fulfills condition

Answer is B.