Answer:
D) x= square root of 89
Explanation:
To find the missing side, use the equation a^2+b^2=c^2. You would plug 5 in for a to get 25 and 8 in for b to get 64. You would add those to get that 89 is equal to c^2 so you would get c by itself and and find that the answer is D. :)