Points, Lines, and Planes Vocabulary

Vocabulary flashcards covering basic geometric terms, definitions, notation rules, and diagrams for points, lines, planes, segments, and rays.

Point

The simplest figure in Geometry, which technically does not have any size and is represented using $1$ upper-case letter.

Line

A one-dimensional figure that extends infinitely in both directions, represented by $2$ capital letters with an arrow symbol on top.

Plane

A two-dimensional figure that extends infinitely, such as a tabletop or flat wall; noted by $1$ italicized upper-case letter, $3$ upper-case letters with no symbols, or a cursive lowercase letter.

Line Segment

A geometric figure consisting of two endpoints and all points in between.

Ray

A geometric figure consisting of an initial point and all points to one side.

Opposite Rays

Rays that share an initial point and extend in opposite directions.

Collinear Points

Points that lie on the same line.

Coplanar Points

Points (figures) that lie on the same plane.

Ray Notation Rule

Notated using $2$ capital letters with a ray symbol (always pointing right) on top, where the $1^{\text{st}}$ letter must be the initial point and the $2^{\text{nd}}$ letter can be any other point on the ray.

Line Segment Notation Rule

Notated using $2$ capital letters with a line segment on top (no dots, no arrows); letter order does not matter, but the letters must be the endpoints.