Identify this figure.

init({
range: [ [-6, 6], [-6, 6] ],
scale: 20
});

line( END1, END2 );
circle( END1, DOT_ATTRS );
circle( END2, DOT_ATTRS );

Line segment

- Line segment
- Ray
- Line

This one-dimensional figure has two endpoints and a set length (it doesn't go on forever).

A 1D figure that has two endpoints and a set length is a *line segment*.

line( END1, END2, { arrows: "->" } );
circle( END1, DOT_ATTRS );
circle( INNER2, DOT_ATTRS );

Ray

This figure is one-dimensional and has one endpoint. It goes on forever in the other direction, though.

Therefore, this figure is a *ray*.

line( END1, END2, { arrows: "->" } );
line( END2, END1, { arrows: "->" } );
circle( INNER1, DOT_ATTRS );
circle( INNER2, DOT_ATTRS );

Line

This figure is straight, one-dimensional, and it goes on forever in both directions. It doesn't have any endpoints.

That description means this figure is a *line*.