A tangent to a circle is:

In geometry, a **tangent** to a circle is a straight line that touches the circle at exactly one point. This point is known as the **point of contact**. A fundamental theorem in circle geometry states that the tangent at any point on a circle is **perpendicular** to the radius through the point of contact. 1. Let the circle have center $O$ and the point of contact be $P$. 2. The line segment $OP$ is the radius. 3. The tangent line $L$ passing through $P$ forms a right angle ($90^\circ$) with $OP$. Mathematically, this is expressed as: $$Radius \perp Tangent$$ Evaluating the other options: - **Coincident with a chord**: False. A chord connects two points *inside* or on the circle; a tangent is a line *outside* the circle (except for one point). - **Parallel to the radius**: False. The radius and tangent intersect at the point of contact; lines that intersect cannot be parallel. - **Twice the radius**: False. This describes the length of the diameter, whereas a tangent is a line.