
Postulate 21
Through any 2 points there is exactly 1 line

Postulate 22
Through any 3 collinear points there its exactly 1 plane

Postulate 23
A line contains at least 2 points

Postulate 24
A plane contains at least 3 points, not all on the same line

Postulate 25
If 2 points lie on a plane, then the entire line containing those 2 points lies in that plane

Postulate 26
2 lines intersect in exactly one point

Postulate 27
2 planes intersect in a line

Midpoint Theorem
If M is mp of (segment) AB then (segment) AM is congruent to (segment) MB

Ruler Postulate
The points on any line or line segment can be paired with real numbers so that given any 2 points, A and B on a line, A corresponds to zero, and B corresponds to a positive real number

Segment Addition Postulate
 If A, B and C are collinear and B is between A and C, then AB + BC= AC.
 If AB+BC=AC then B is between A and C.

Theorem 2.2
Congruence of segments is reflexive, symmetric & transitive

Protractor Postulate
Given (ray) AB and a number r between 0 and 180, there is exactly one ray with endpoint A, extending on either side of (ray) AB, such that the measure of the angle formed is r.

Angle Addition Postulate
If R is in the interior of <PQS then the m<PQR and the m<RQS= the m<PQS

Supplement Theorem
If 2 <'s form a linear pair, then they are supplemenetary

Complement Theorem
If the noncommon sides of 2 adjacent angles form a right angle, then the angles are complementary angles.

Theorem 2.6
Angles supplementary to the same angle or to congruent angles are congruent

Theorem 2.7
Angles complementary to the same angle or to congruent angles are congruent

Theorem 2.9
Perpendicular lines intersect to form 4 right anlges

Theorem 2.10
ALL right angles are congruent

Theorem 2.11
Perpendicular lines form congruent adjacent angles.

Theorem 2.12
If 2 <'s are congruent and supplementary, then each angle is a right angle

Theorem 2.13
If 2 congruent <'s form a linear pair, then they are right angles.

Vertical Angles's Theorem (2.8)
Vertical Angles are Congruent

