Undefined Terms:
Point, Line and Plane.
Axioms:
 Two points A and B determine a unique line,
to be denoted by AB.
 (The Distance Axiom). To every pair of distinct points
there corresponds a unique positive number, called their distance.
This distance satisfies the requirement of the next axiom.
 (The Ruler Axiom). Every line can be put in
oneone correspondence with the real numbers so that if
P and Q are two points on the line, then the absolute value
of the difference of the corresponding real numbers is
the distance between them.
 (The Ruler Placement Axiom). Given two points P and Q
on a line, the correspondence with real numbers in
the preceding axiom can be chosen so that P corresponds
to zero and Q corresponds to a positive number.
 There are at least three noncollinear points.
 (The Plane Separation Axiom). Given a line L.
Then the points not on L form two convex sets,
and any line segment AB joining a point A in one set
and a point B in the other must intersect L.
The convex sets are called the halfplanes determined by L.
 (The Angle Measurement Axiom). To every
ABC
there corresponds a real number between 0 and 180,
to be denoted by mABC,
called the measure of the angle.
 (The Angle Construction Axiom). Given a line AB
and a halfplane H determined by AB, then for every number r
between 0 and 180, there is exactly one ray AP in H
so that mPAB = r.
 (The Angle Addition Axiom). If D is a point
in the interior of BAC, then
mBAC =
mBAD +
mDAC.
 (The Parallel Axiom). Through a given external point,
there is at most one line parallel to a given line.
 (The Area Axiom). To every polygonal region,
there corresponds a unique positive number,
called its area, with the following properties:
(i) congruent triangles have the same area;
(ii) area is additive on disjoint unions; and
(iii) the area of a rectangle is the product of
the lengths of its sides.
 (The Angle Supplement Axiom). If two angles
form a linear pair, then their measures add up to 180.
 SAS Axiom for congruence of triangles.
 SSS Axiom for congruence of triangles.
 ASA Axiom for congruence of triangles.
 (The AA Axiom for Similarity). Two triangles
with two pairs of angles equal are similar.
