If a line is a tangent to a circle, then it is [[1]] to the radius drawn to the point of tangency.

If a line is a tangent to a circle, then it is perpendicular to the radius drawn to the point of tangency.

A tangent to a circle is a line intersecting the circle at exactly one point, the point of tangency or tangency point. An important result is that the radius from the centre of the circle to the point of tangency is perpendicular to the tangent line