Theorem: When two secants meet at an external point, the products of the secant and the external segment are equal.
In essence, we are saying that QR × PR = TR × SR
Thus, 16 × 6 = 8(x + 8)
96 = 8(x + 8)
Dividing both sides by 8, we produce:
12 = x + 8
x = 4
Thus, we can conclude that the missing side, x, is 4.