1. Use segments and congruence
Lesson 1.2
Use segments and congruence

2. Objective
Use segment postulates to identify congruent segments.

3. Standard
1.0 – Students demonstrate understanding by identifying and giving examples of undefined terms, axioms, theorems, and inductive and deductive reasoning.

4. Academic Language

5. Postulate or axiom
A rule that is accepted without proof

6. Postulate 1
The points on a line can be matched one to one with real numbers

7. Coordinate Points Coordinates
the real number that corresponds to a point
Points A B X1 X2
Coordinates

8. Distance
The absolute value of the difference of 2 points A and B, written as AB AB A B X1 X2

9. Example 1
What is the distance between points S and T? S T 2
5.4

10. Indy Practice
What is the distance between points A and B? A B -4 7

11. Adding Segment Lengths
When 3 points are collinear, you can say that one point is between the other two.
Example D F C E B A
Which point is between? Why?

12. Postulate 2 – Segment addition Postulate
If B is between A and C, then AB + BC = AC
If AB + BC = AC, then B is between A and C AC A B C AB BC

13. The Real World
The cities Lubbock, Tulsa, and St. Louis lie approximately in a straight line on a map. Tulsa is between Lubbock and St. Louis, 380 miles from Lubbock and 360 miles from St. Louis. Find the distance from Lubbock, Texas to St. Louis, Missouri

14. Indy Practice
1. Find the length of XZ 2. WY = 30. Can you use segment addition to find the distance between W and Z? Explain 23 50 X Y Z W

15. More Practice
Find GH 36 F 21 G H

16. Congruent Segments
Line segments that have the same length

17. Example
Plot J(-3, 4) K(2, 4) L(1, 3) M(1, -2)
Congruent?

18. Homework
p.12 #1, 2, 3, 11, 13, 17, 21, 29, 33