1. 1.5 Segments & Their Measures

2. Coordinate The real number that corresponds to a point.
A & B are names for the points.
x1 and x2 are coordinates for the points. A B x1 x2

3. Distance The length of AB can be found by x2-x1
The symbol for the length of AB is AB.

4. Example 1: Find AB. A B Point A is at 1.5 and B is at 5.
So, AB = = 3.5

5. When 3 points are on a line, one of them is between the other two.
B is between A & C. A B C

6. Example 1: Is Alex between Ty and Josh?
Yes! Ty
Alex
Josh
No, but why not?
How about now?
In order for a point to be between 2 others, all 3 points MUST BE collinear (on the same line)!!

7. Measure (of a line segment)
The measure of a segment is the distance between the two endpoints. It is written as AB (with no segment over the letters.)

8. A statement that is accepted true without a proof.
Postulate
A statement that is accepted true without a proof.

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

10. Example 3: if DE=2, EF=5, and DE=FG, find FG, DF, DG, & EG.

11. Segments that have the same length. If AB & XY have the same length,
Congruent ( ) Segments
Segments that have the same length.
If AB & XY have the same length,
Then AB=XY,
but
AB XY
Symbol for congruent