What is a ray in geometry?

A ray in geometry is a part of a line that has one endpoint and extends infinitely in one direction. It can be defined by specifying its endpoint and a point that lies on the ray.

Here's some key information about rays:

• Endpoint: A ray has a definite starting point called the endpoint.

• Direction: It extends infinitely in one direction from the endpoint.

• Notation: Rays are often denoted using two points. The first point represents the endpoint, and the second point represents any other point on the ray. For example, ray AB starts at point A and passes through point B, extending infinitely in the direction of B. The notation for this is often written as $\overrightarrow{AB}$.

• Line vs. Ray: A line extends infinitely in both directions, while a ray extends infinitely in only one direction.

• Applications: Rays are used in various geometric concepts, including:

  • Angles: An angle is formed by two rays sharing a common endpoint (the vertex).
  • Light rays: In physics, light is often modeled as traveling in straight lines, which can be represented as rays.