What is the definition of a tangent in relation to a circle?

A tangent to a circle is defined as a line that touches the circle at exactly one point. This single point of contact is known as the point of tangency. The defining characteristic of a tangent is that while it approaches the circle, it does not enter or cross into the interior of the circle—rather, it only "glances" off at that single point.

The other descriptions do not accurately depict a tangent's behavior: a line that intersects the circle at two points would be a secant, while a line that doesn’t touch the circle at all does not meet the criteria for being a tangent. Additionally, the statement regarding forming a right angle with the radius is a property related to tangents, but it does not represent the fundamental definition of what a tangent is. In essence, the defining aspect of tangents is their singular point of contact with the circle, aligning perfectly with the correct answer.