Answer:
14√2
Step-by-step explanation:
A square with a diagonal automatically makes a 45 45 90 triangle (angles) meaning that the two legs are x and the hypotenuse (diagonal) is x√2
If 14 = x then the diagonal is 14√2
You could also solve with the pythagorean theorem
a^2 + b^2 = c^2 so in this case
14^2 + 14^2 = c^2
196 + 196 = c^2
392 = c^2
√392 = √c^2 the 392 is divisable by 196 so you can divide that out as 14
14√2 = c