Answer:
Angle → Defined
Ray → Defined
Segment → Defined
Point → Undefined
Triangle → Defined
Line → Undefined
Plane → Undefined
Explanation:
In geometry, the following terms are defined:
- Angle: An angle is formed by two rays with a common endpoint. The common endpoint is called the vertex of the angle.
- Ray: A ray is a part of a line that has one endpoint and extends infinitely in the other direction.
- Segment: A segment is a part of a line that has two endpoints.
- Triangle: A triangle is a polygon with three sides and three angles. three sides and three angles.

The following terms are undefined:
- Point: A point is a location in space that has no size.
- Line: A line is a one-dimensional figure that has no thickness and extends infinitely in both directions.
- Plane: A plane is a two-dimensional figure that has no thickness and extends infinitely in all directions.