how do i find the length of the third side?

Answer: 6
Step-by-step explanation: since this is a right triangle, you can use pythagorean theorem to solve this. which is a^2 + b^2 = c^2
lets say a=5 and b=root11
you would plug this into the equation -> (5)^2 + (root11)^2 = 25 + 11 which is 36 which is c^2. to get c from c^2, you'd take the square root of c^2 (which in this case is 36) to give you 6.
6 is the length of the third side