WILL GIVE BRAINLIEST ANSWER TO WHOEVER ANSWERS FIRST AND CORRECTLY EXPLAIN WHY YOURE CORRECT

Answer:
9
Step-by-step explanation:
If you use Patagonian's therom a^2+b^2=c^2 you get
5^2+8^2=89
you need to get the root of 89 to get the answer witch is 9.433981 but you round to the nearest whole number so it's 9