This unit defines congruent segments, gives the properties of congruency and gives formulas for midpoints in 1 dimension.

1. Section 2.3

2.  Two segments are congruent if and only if
they have the same length.
 Below AB ≅ CD (“≅” means “is congruent to”)
2 cm B C 2 cm
A D

3.  Theorems are statements derived by logical
argument using definitions and accepted facts.
 Primary Theorems of segments
Congruence of Segments is: Meaning:
Reflexive AB ≅ AB
Symmetric If AB ≅ CD, then CD ≅ AB
If AB ≅ CD & CD ≅ EF,
Transitive
then AB ≅ EF

4.  A Midpoint is the point that is the same
distance from each endpoint
 For a segment with endpoints A an B, it is
found using the formula:
M=½(A+B) B
M
A

5.  Length
AB = ∣ B – A ∣ B
M
 Midpoint length formulas
A
AM = MB
AM = ½ AB
MB = ½ AB