Answer:
x = 5
Step-by-step explanation:
Given a tangent and a secant from an external point to the circle.
Then the square of the tangent is equal to the product of the external part and the whole of the secant, that is
8(5x - 1 + 8) = 16², that is
8(5x + 7) = 256 ( divide both sides by 8 )
5x + 7 = 32 ( subtract 7 from both sides )
5x = 25 ( divide both sides by 5 )
x = 5
