Answer:
x = 12 cm
Step-by-step explanation:
The product of lengths from the secant intersection point to the "near" and "far" circle intersection points is the same for both secants. When one "secant" is a tangent, the lengths to the circle intersection points are the same (so their product is the square of the tangent segment length).
8^2 = 4·(4 +x) . . . . . . measures in centimeters
16 = 4 +x . . . . . . divide by 4
12 = x . . . . . . . . . subtract 4
