Answer:
![x=40\ units](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ifsxu5dk8xus365ducr52u01k6spj8c9ac.png)
Explanation:
see the attached figure to better understand the problem
we know that
segment BC is a tangent to the circle at point B ---> given problem
AB is a radius of the circle
The tangent BC is perpendicular to the radius AB
Remember that
According to the Perpendicular Tangent Theorem, tangent lines are always perpendicular to a circle's radius at the point of intersection
so
The triangle ABC is a right triangle
Applying the Pythagorean Theorem
![AC^2=AB^2+BC^2](https://img.qammunity.org/2020/formulas/mathematics/high-school/gu26ic3sn5r1uk2g4pjfipow4dkt1mi3bc.png)
substitute the given values
![41^2=9^2+x^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8imjgp2eiaxr37ghzwrh1osbrukld0apk4.png)
solve for x
![1,681=81+x^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/564mwkl9jubxb9irfbatw53dfv9o93id7v.png)
![x^2=1,681-81](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ykw6z1ehdnk4k3gbl0dc7g3a6hli0pj9sb.png)
![x=40\ units](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ifsxu5dk8xus365ducr52u01k6spj8c9ac.png)