1. Do Now:
Using the picture below, decide whether the statements are true or false.

2. 1.2: Use Segments and Congruence
Geometry
1.2: Use Segments and Congruence

3. Vocabulary
Postulate (Axiom): a rule in geometry that is accepted without proof.
Theorem: a rule that can be proved.

4. Ruler Postulate
The distance between two points A and B, written as AB, is the absolute value of the difference of the coordinates A and B.

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

6. Examples 1) Find the length of AC 2) Find the length of BC
AC = AB + BC
AC = 5 +14
AC =19
2) Find the length of BC
BC = AC – AB
BC = 38 – 17
BC = 21

7. Real-Life Example
Distance from Lubbock to St. Louis is about 740 miles.

8. Examples Involving Algebra
Write an expression to represent the length of AC
AC = AB + BC
AC = x x + 3
AC = 3x + 9
2) Find the value of x:
27 = 3x+9
18 = 3x 3
x = 6

9. Congruent Segments
If line segments have the same length, then the segments are congruent.
AB = CD AB CD

10. Compare Segments for Congruence

11. HOMEWORK
Text p12-13: # 3, 6, 9, 13, 21-26