CD and ED are both radii of the circle, meaning they are equal to each other and equal x.
We can use the Pythagorean Theorem:
8^2 + x^2 = (4 + x)^2
64 + x^2 = 16 + 8x + x^2
Subtract x^2 and 16 from both sides:
8x = 48
x = 6
The answer is (B).
