FTCE General Knowledge Math Practice Test

Which line intersects a circle at exactly one point?

1. Chord

2. Radius

3. Secant

4. Tangent line

The correct answer is: Tangent line

The line that intersects a circle at exactly one point is the tangent line. A tangent line touches the circle at just one point, known as the point of tangency, and does not enter the interior of the circle. This characteristic is fundamental to tangent lines, as they provide a specific relationship between the circle and the line, indicating that at the point of intersection, the line is perpendicular to the radius drawn to that point. In contrast, a chord is a line segment with both endpoints on the circle, therefore intersecting at two points. A radius is a line segment drawn from the center of the circle to a point on its circumference, which also means it intersects at exactly one point, but it does not specialize in the tangent's unique relationship of being outside the circle except at that one point. A secant, on the other hand, intersects the circle at two points, as it passes through the interior of the circle. Thus, the distinct property of the tangent line defines its role in relation to the circle.