# Unit 1: Points, Lines and Planes Vocabulary

## 21 terms

### point

It marks a location and is named by a capital letter; it has no thickness and 0 dimension.

### line

An infinite set of points that goes on forever; it has no thickness and it is one dimensional.

### plane

A flat surface that goes on forever in two directions; an infinite set of points; it has no thickness and is two dimensional.

### space

The set of all points. It is three dimensional.

### collinear

Points that lie on the same line.

### noncollinear

Points that do not lie on the same line.

### coplanar

Points that lie on the same plane.

### noncoplanar

Points that do not lie on the same plane.

### intersection

The set of points both figures have in common.

### segment

Part of a line consisting of two end points and all the points between them.

### ray

Part of a line that starts at a particular point and extends infinitely in one direction.

### perpendicular

Two lines that intersect to form right angles.

### parallel

Lines that do not intersect but are in the same plane.

### skew

Lines that are not parallel and do not intersect.

### opposite rays

Two rays that share a common endpoint but extends in opposite directions and makes a line.

### congruent segments

Segments that have the same length.

### midpoint

A point that divides a segment into two congruent segments.

### endpoint

Marks the end of a line segment or ray.

### segment bisector

A line that divides a segment at its midpoint to form two congruent segments.

### perpendicular bisector

A line that passes through the midpoint of a segment and is perpendicular to that segment.

### intersecting lines

Two lines that cross at a given point.