What term describes a line in the plane of a circle that intersects the circle in exactly one point?

What term describes a line in the plane of a circle that intersects the circle in exactly one point?

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

Answer: (A)

The line that touches a circle at exactly one point is called a tangent. This single-touch behavior distinguishes it from a secant, which cuts through the circle at two points, and from a chord, which is a line segment connecting two points on the circle. A radius, on the other hand, is a line from the circle’s center to a point on its edge. The tangent line meets the circle at one point, and the radius to that point is perpendicular to the tangent, reinforcing why this is the correct term.

The line that touches a circle at exactly one point is called a tangent. This single-touch behavior distinguishes it from a secant, which cuts through the circle at two points, and from a chord, which is a line segment connecting two points on the circle. A radius, on the other hand, is a line from the circle’s center to a point on its edge. The tangent line meets the circle at one point, and the radius to that point is perpendicular to the tangent, reinforcing why this is the correct term.