Postulates and Paragraph Proofs

Section 2-5

postulate or axiom – a statement that describes a fundamental relationship between the basic terms of geometry. Postulates are accepted as true.

proof – a logical argument in which each statement you make is supported by a statement that is accepted as true.

theorem – a statement or conjecture that has shown to be true.

Postulates2.3 A line contains at least 2 points.

2.4 A plane contains at least 3 points not on the same line.

2.5 If 2 points lie in a plane, then the entire line containing those points lies in that plane.

2.6 If 2 lines intersect, then their intersection is exactly one point.

2.7 If 2 planes intersect, then their intersection is a line.

Midpoint Theorem (2.8) If M is the midpoint of , thenAB

AM MB

AM

B

5 Parts of Good ProofState theorem or conjecture to be

proved.List the given information.Draw a diagram if possible.State what is to be proved.Develop a system of deductive

reasoning.