Answer:
3.2
Step-by-step explanation:
If there are 2 secont lines intersecting inside a circle like the picture shown, then the theorem tells us that "the product of 2 segments of one secant line is equal to the product of 2 segments of other secant line"
Thus, we can say that:
x * 10 = 8 * 4
10x = 32
x = 32/10
x = 3.2
