This document defines key concepts about line segments and congruence. It introduces coplanar points, ways to write line segments, and the segment addition postulate which states that if point B lies between points A and C on a line, then the length of AB plus BC equals the length of AC. It also defines congruent segments as line segments with the same length and provides examples of using the segment addition postulate and defining congruent segments. The document assigns homework problems applying these concepts.

1. 1.2 Segments and Congruence 8­23­10
Bellwork
1. Give definition of coplanar points. points that are on the same plane
2. What is another way to write line segment AB? BA or AB
3. Sketch a plane and two intersecting lines that lie in the plane.
# 4 & 5
Y
W V
X
4. What is another name for ZY? YZ Z
5. A student says the VW and VZ are opposite rays because they
have the same endpoint. Describe the error.
Point V must lie between points W and Z, which means the 3 points must be collinear.
HW pg.9 #6­11, 13­17, 24­27 1

2. 1.2 Segments and Congruence 8­23­10
1.2 Segments and Congruence
Postulate: A rule that is accepted w/o proof
Theorem: A rule that can be proved
Ruler Postulate: Points on a line can be matched with
real numbers (AKA coordinate)
Names of Points
A B
x1 x2
Coordinates of Points
Distance = absolute value of the difference
AB
A B
x1 x2
AB = x2 - x1
HW pg.9 #6­11, 13­17, 24­27 2

3. 1.2 Segments and Congruence 8­23­10
HW pg.9 #6­11, 13­17, 24­27 3

4. 1.2 Segments and Congruence 8­23­10
Segment Addition Postulate: If B is between A & C,
then AB + BC = AC.
*between: the point in the middle of 2 collinear points on
the same line A
B
C
AC
A B C
AB BC
HW pg.9 #6­11, 13­17, 24­27 4

5. 1.2 Segments and Congruence 8­23­10
HW pg.9 #6­11, 13­17, 24­27 5

6. 1.2 Segments and Congruence 8­23­10
HW pg.9 #6­11, 13­17, 24­27 6

7. 1.2 Segments and Congruence 8­23­10
HW pg.9 #6­11, 13­17, 24­27 7

8. 1.2 Segments and Congruence 8­23­10
36
Find Length
F G H
21
FH = FG + GH (Segment Addition Postulate)
36 = 21 + GH
36-21 = GH
15 = GH
Congruent Segements: line segments w/ same length
Equal Congruent
A B
C D AB = CD AB ≅ CD
HW pg.9 #6­11, 13­17, 24­27 8

9. 1.2 Segments and Congruence 8­23­10
HW pg.9 #6­11, 13­17, 24­27 9

10. 1.2 Segments and Congruence 8­23­10
HW pg.9 #6­11, 13­17, 24­27 10

11. 1.2 Segments and Congruence 8­23­10
HW: p 12
# 6-11
13-17
24-27
HW pg.9 #6­11, 13­17, 24­27 11