1. Geometry
2.3 Proving Theorems

2. Intro
 Theorems are statements that are proved.
 They are deduced from postulates, statements
that are accepted without proof.
 POE’s are treated as postulates
 Deductive Reasoning uses postulates
defn.’s, thm.’s, and given information.
Hint: deductive = definition

3. 5 Reasons Used in Proofs
 Given Information
 Defn.’s
 Postulates(POE’s)
 Theorems from yesterday i.e.(that is)
theorems that have been proven
 Properties

4. Midpoint Thm.

A
.
M
.
B
.

5. 
.
Y
.
A
.
B

6. Angle Bisector Them.

.
C
B .
. X
. A

7. Angle Bisector Thm. Versus the Angle Bisector
Defn.

.
C
B.
. X
. A