In mathematics, a ray is a part of a line that has one endpoint and extends infinitely in one direction.
Understanding Rays
A ray is a fundamental concept in geometry. It's essential to distinguish it from a line and a line segment. According to the YouTube video "What is the Ray in Geometry? | Ray Vs. line segment...#short ...", a ray has one endpoint and extends infinitely in one direction, indicated by an arrowhead.
Key Characteristics of a Ray:
- Endpoint: A ray has a definite starting point.
- Direction: It extends infinitely in one direction.
- Notation: A ray is often denoted by naming its endpoint and another point on the ray, with an arrowhead above the two letters indicating the direction of extension (e.g., Ray AB). The endpoint is always listed first.
Example:
Imagine a ray starting at point A and passing through point B. This ray would be written as $\overrightarrow{AB}$, with the arrowhead pointing towards B, indicating the direction of infinite extension. The video confirms that this notation signifies Ray AB, where A is the endpoint, and the ray extends through point B infinitely.
Comparison with Lines and Line Segments:
| Feature | Line | Line Segment | Ray |
|---|---|---|---|
| Definition | Extends infinitely in both directions | Has two endpoints | Extends infinitely in one direction |
| Endpoints | None | Two | One |
| Representation | $\overleftrightarrow{AB}$ | $\overline{AB}$ | $\overrightarrow{AB}$ |
