Which geometric concept refers to a line that touches a circle at exactly one point?

Which geometric concept refers to a line that touches a circle at exactly one point?

• A. Tangent
• B. Secant
• C. Chord
• D. Radius

Answer: (A)

A line that touches a circle at exactly one point is called a tangent. This touch point is the point of tangency, and the radius drawn to that point is perpendicular to the tangent line. If a line passes through the circle in two points, it’s a secant. The line segment inside the circle joining two points on the circle is a chord, and a radius is the segment from the circle’s center to a point on the circle. The tangent property—perpendicularity to the radius at the point of contact—helps distinguish it from the other ideas.

A line that touches a circle at exactly one point is called a tangent. This touch point is the point of tangency, and the radius drawn to that point is perpendicular to the tangent line. If a line passes through the circle in two points, it’s a secant. The line segment inside the circle joining two points on the circle is a chord, and a radius is the segment from the circle’s center to a point on the circle. The tangent property—perpendicularity to the radius at the point of contact—helps distinguish it from the other ideas.