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 Description  
 Ray:  A ray begins at a point and goes on forever in one direction.
A ray is a line with a starting point but no endpoint.


The figure above is an example of a ray. Two letters are needed to name a ray: one names the point where the ray begins and the other names any point the ray passes through.

The symbol for a ray is the two letters with an arrow on top. Notice that ray AB is not the same as ray BA.