# Geometry: Defined Terms

### 23 terms by slowen

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Alpha Omega Geometry

### betweenness of points

A condition of one point being between two other points on a line.

### bisector of a segment

A line or segments that intersects a segment at its midpoint.

### collinear points

Occuring on the same line.

### complement of a set

The elements in the universe that are not in the set.

### coplanar points

Occuring on the same plane.

### disjoint sets

Sets that have no common elements.

### element

An object that belongs to a set. Sometimes the word "member" is used.

### empty set

A set that has no elements. It is sometimes called the null set.

### finite set

Any set whose elements can be counted.

### geometry

From the Greek for "earth measure."

### infinite set

Any set whose elements cannot be counted.

### intersection of sets

A set containing elements in common for all sets being considered.

### length of a segment

The distance between the endpoints of a segment.

### line segment

The set of two points and all points between.

### midpoint of a segment

A point that divides a segment into two equal segments.

### postulate

A statement accepted without proof.

### opposite rays

BA and BC are opposite rays if A, B, and C are collinear and B (the endpoint of both rays) is between A and C.

### proper subset

A subset that does not contain every element in another set.

### set

A collection or group of objects.

### space

The set of all possible points.

### subset

A set that contains only elements found in another set.

### union of sets

A set containing all elements of all sets being considered.

### ray

a part of a line extending from one endpoint and continuing in one direction indefinitely

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