Geometry · Points, Lines & Angles
Ray
HSG-CO.A.1
Definition
A part of a line with one endpoint that extends infinitely in one direction.
Examples
- Ray AB starts at endpoint A, passes through B, and continues forever in one direction.
- Ray BA would start at B and extend through A and beyond — a different ray than ray AB.
Key rule
A ray has exactly one endpoint and extends forever in only one direction.
Memory hook
One end fixed, the other end never stops.