9514 1404 393
Answer:
C. 17.25
Step-by-step explanation:
The product of distances from the common point to the two circle intersection points is the same for each secant.
5(5+12) = 4(4+a)
69 = 4a . . . . . . . . subtract 16, simplify
17.25 = a . . . . . . . divide by 4
