Which formula can be used to describe the relationship between a tangent line and the radius of a circle at the point of tangency?

The relationship between a tangent line and the radius of a circle at the point of tangency is defined by the fact that they compose a right angle. Specifically, when a radius meets a tangent line at the point where the tangent touches the circle, it creates an angle of 90 degrees. This fundamental property of circles is an essential aspect of geometry, highlighting the perpendicular nature of the radius with respect to the tangent line at the point of tangency.

This perpendicular relationship is crucial for several geometric proofs and constructions. For example, it can be used to determine the positions of points in relation to the circle or to solve problems involving circles within coordinate geometry. Understanding this principle allows for deeper insights into the nature of circles and is a fundamental aspect of both Euclidean geometry and advanced mathematical concepts.