9514 1404 393
Answer:
8
Explanation:
The product of segment lengths to the near and far circle intersection points is the same for both "secants". AD is a tangent, so the two intersection points are the same point. This gives ...
AD² = AB·AC
144 = AB(AB +10)
We can add 25 to complete the square.
169 = (AB +5)² . . . write as a square
13 = AB +5 . . . . . . positive square root
8 = AB . . . . . . . . . .subtract 5