Math

Undefined Terms

Terms whose meanings are accepted without formal definition. The terms point, line and plane are undefined terms that are the basic building blocks of geometry.

Point

A location in space with no size or dimension, representing a precise position.

Line

An infinite number of points on a straight path that extends in two opposite directions with no end and has no thickness.

Plane

Infinite number of points and lines on a flat surface that extends without end and has no thickness.

Defined Terms

New terms are defined using previously defined or known terms.

Segment

The part of the line that consists of two points, called endpoints and all points between them.

Ray

The part of a line that consists of one endpoint and all the other points of the line on one side of the endpoint.

Opposite rays

Rays with the same endpoint that lie on the same line.

Angle

Angle is formed by two rays with the same endpoint. Each ray is a side of the angle and the common endpoint is the vertex of the angle.

Ruler Postulate

Every point on a line can be paired with a unique real number. This number is called the coordinate of the point

Distance on a line

The distance between any two points X and Yay! is the absolute value of the difference of their coordinates.

Segment Addition Postulate

If points A, B, and C are on the same line with B between A and C, then AB + BC = AC

Protractor Postulate

Given ray BA and a point C not on ray BA, a unique real number from 0 to 180 can be assigned to ray BC. 0 is assigned to ray BA. 180 is assigned to ray BD.

Angle Addition Postulate

If point D is in the interior of angle ABC, then measure of angle ABD + measure of angle DBC = measure of angle ABC.