Answer:
9√2
Explanation:
To do this, we need to use the Pythagoras' Theorem. Which is a^2+b^2=c^2
In this case, we need to solve for C. So, we do 9^2 (A) +9^2 (B), assuming a and b are the same. So we end up with 81+81=c^2. Now, we find the square root of 162. Around 13 or 9√2