Answer:
y = 11.5
Explanation:
Given 2 secants from an external point to the circle.
Then the product of the external part and the whole of one secant is equal to the product of the external part and the whole of the other secant, that is
6(6 + y) = 5(5 + 16)
36 + 6y = 5 × 21 = 105 ( subtract 36 from both sides )
6y = 69 ( divide both parts by 6 )
y = 11.5