1. Geometry Notes
Section 1-2

2. What you’ll learn How to define postulate
How to identify and model line segments
How to apply the Segment Addition Postulate
How to compute with measures
How to identify congruent segments

3. Vocabulary Terms: Postulate Line segment Betweeness of points Between
Segment Addition Postulate
Unit Conversion
Congruent Segments

4. Postulates Geometry is based on accepted rules and proven theories.
Postulate is the term used for rules that are assumed to be true (postulates do not have to be proven).

5. Line Segment—a section of a line from one endpoint to another endpoint
Draw it with 2 dots (one at each end) and a straight line between them P Q
Name it by the endpts (with above)
Fact: Segments are measureable. They have a beginning and end. The measure of a segment is written by naming the endpts with capital printed letters (PQ means the measure of PQ)
Words/Symbols: PQ

6. Segments are measured with a ruler, yardstick or tape measure
Segments have measure
Segments are measured with a ruler, yardstick or tape measure
Units of measure include
Inches
Feet
Yards
Centimeters
Meters

7. Unit Conversion Standard
Students will be able to convert units of measurement within and between systems
Within the same system
Like inches to feet
Between systems
Like inches to centimeters

8. Betweeness
There are infinitely many points between the endpoints of a line segment G O
For Example
Given DG D
Would it be fair to say O is between D and G?
What relationships do you see between the points?
Do the points have to be collinear?
Is there some connection between the measures DO, OG and DG?

9. Betweeness and the Segment Addition Postulate
O is between D and G if and only if
D, O , and G are collinear
DO + OG = DG

10. Congruent Segments Congruent figures have the same size and shape
Since all segments have the same shape we only need to verify that two segments have the same measure to be congruent
Definition of Congruent Segments:
Two segments are congruent if and only if they have the same measure.
Using symbols: AB  CD iff AB = CD A B C D

11. Have you learned. . . How to define postulate?
How to identify and model line segments?
How to apply the Segment Addition Postulate?
How to compute with measures?
How to identify congruent segments?
Your assignment is Worksheet 1.2