X kaç cmdir?

Question

Answer 1

$$|OC|^2=|CE|^2+|EO|^2|\Rightarrow r^2=x^2+8^2$$

ve 

$$|OD|^2=|DF|^2+|FO|^2|\Rightarrow r^2=(x+2)^2+5^2$$

ise $x=?$