Question

which figure represents an undefined term?

Explanation:

Step1: Recall undefined terms in geometry

In geometry, the undefined terms are point, line, and plane. A line is a straight path that extends infinitely in both directions.

Step2: Analyze each figure

• First figure: A ray (has one endpoint, extends infinitely in one direction) – not an undefined term (ray is defined using line and point).
• Second figure: A line segment (has two endpoints, finite length) – defined using points, not undefined.
• Third figure: Two rays with a common endpoint (an angle or two rays) – defined using rays, hence defined.
• Fourth figure: A line (arrows on both ends, extends infinitely in both directions) – this is one of the undefined terms (line) as it is not defined in terms of other geometric concepts but is a fundamental building block.

Answer:

The fourth figure (the one with arrows on both ends, passing through points \( X \) and \( Y \))