THERE IS NO PICTURE TO ANSWER THIS
Answer:
-9
Step-by-step explanation:
= 
Answer:
If AB is a tangent to the circle, the triangle ABO is right angled, as the angle where a tangent meets the circumference is always 90 degrees.
We also know that Pythogoras' theorem only holds for right angled triangles.
The hypotenuse is 12 + 8 as 12 is the radius so is 20.
16^2+12^2 = 256 + 144 = 400 = 20^2 so AB must be tangent.
We have a right triangle with a 15m hypotenuse and a 8m leg. If we use x for the missing leg then the Pythagorean Theorem states that:

Then we have to solve that equation for x:
![\begin{gathered} x^2=15^2-8^2=225-64 \\ x^2=161 \\ x=\sqrt[]{161} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20x%5E2%3D15%5E2-8%5E2%3D225-64%20%5C%5C%20x%5E2%3D161%20%5C%5C%20x%3D%5Csqrt%5B%5D%7B161%7D%20%5Cend%7Bgathered%7D)
So the answer is the square root of 161.