Answer:
x = sqrt(17)
Explanation:
Angle B is 90 degrees; the line BC is a radius of circle C and line AB is a tangent line of BC. Since they must be perpendicular, angle B is 90 degrees.
Now use the pythagorean theorem to solve for x.
c=9, a = 8, b= x
a^2+b^2=c^2
8^2+x^2=9^2
x=sqrt(81-64)
x=sqrt(17)