1. Chapter 1 : Essentials of Geometry
1.2 Use Segments and Congruence

2. Postulates or axiom
Postulates or axioms are rules of geometry that we accept as true without any proof.

3. Ruler Postulate Each point on a number line have a unique value
The distance between two points A and B (AB) is equal to |A-B|

4. Segment Addition Postulate
If Y is between X and Z, then
XY + YZ = XZ

5. Equality (=) vs. Congruence()
Objects such as a segment or an angle have a specific measurement associated with it. These measurements have numeric values which can be added, subtracted, multiplied, or divided.
The objects themselves CAN NOT be added,
subtracted, multiplied, or divided. However they can
be COMPARED to one another. Objects can be similar
(same shape and proportional size) or congruent
(same shape and same size).

6. Congruent Segments Congruent Segments have the exact same shape (both
are segments) and exact same size (length). Segments
are congruent, lengths are equal.