Answer: 6
Step-by-step explanation:
Constructing the altitude of triangle ABC from point A, we get that by the Pythagorean theorem,
h^2 = (AC)^2 - (BC/2)^2 -> h=48.
So now, we know that once again by the Pythagorean theorem,
(CD+14)^2 = (AD)^2 - h^2
(CD+14)^2 = 400 -> CD=6
