Definitions, Theorems, Axioms, Postulates, and Properties Flashcards
theorem
properties/facts that have been established with proof
postulate/property/axiom
properties/facts accepted without proof
Line Axiom
There are infinitely many points A, B, C,…, and infinitely many lines l, m, n, … .
Two points determine a line:
(1) Given any two distinct points, exactly one line contains them both.
(2) Each line contains at least two points.
Given a line, there exists a point not on the line.
The Distance Assignment Postulate
(i) To every pair of distinct points there corresponds a unique positive number. The number is called the distance between the two points.
(ii) The distance between two points is zero if and only if the two points are not distinct.
The Segment Existence Postulate
Given ray XY and line segment AB, there exists exactly one point P on ray XY such that line segment XP is congruent to line segment AB.
Line Segment Extension Postulate
Given any 2 distinct points A and B, there exists a point C such that A, B, and C are collinear and C is not between A and B.
Angle Measure Assignment Postulate
To every angle there corresponds a unique real number between 0 and 180. This number is called its measure.
Angle Existence Postulate
Given ray XY, a point P on one side of line XY, and a real number k between 0 and 190, there exists exactly one ray, XP, such that the measurement of angle PXY is equal to k.
The Partition Postulate
A whole is equal to the sum of its parts.
(1) If point B is between points A and C, then AB + BC = AC.
(2) If P lies in the interior of angle ABC, then the measurement of angle ABP plus the measurement of angle PBC is equal to the measurement of angle ABC.
Some More Existence Postulates
a) . Each line segment has a unique midpoint.
b) . Each angle has a unique angle bisector.
The Addition Postulate of Algebra
If equals are added to equals then their sums are equal.
Substitution Postulate
We may replace an expression with an equivalent expression in any statement.
The Addition Theorem of Congruence
If congruent segments (angles) are added to congruent segments (angles) then their sums are congruent.
The Subtraction Postulate of Algebra
If equals are subtracted from equals then their differences are equal.
The Subtraction Theorem of Congruence
If congruent segments (angles) are subtracted from congruent segments (angles) then their differences are congruent.
The Transitive Property for Congruence
If two line segments (angles) are congruent to the same line segment (angle) then they are congruent to each other.
The Reflexive Property for Congruence
A line segment (angle) is congruent to itself.
The Symmetric Property for Congruence
A congruence is reversible.
Note: The symmetric property differs from Reversibility of Notation, which tells us that line segment SW and line segment WS name the same segment.
The Multiplication Postulate of Algebra
If a = b then ca = cb.
The Division Postulate of Algebra
If a = b then a / c = b / c (provided that c is not equal to zero).