Problem #DES-020324

Problem

Generally, when a line intersects a circle, it creates two different points of intersection. However, sometimes there is only one point. In such case we say the line is tangent to the circle. For example on the picture below the line $CD$ intersects the circle at two points $D$ and $E$ and the line $CB$ is tangent to the circle. To solve the problems today we will need the following theorem.
Theorem: The radius $AB$ is perpendicular to the tangent line $BC$.