section 1.3 segments & their measures 1/14. geometric vocabulary postulate : rules that are...
TRANSCRIPT
Section 1.3Segments & Their
Measures
1/14
Geometric Vocabulary
Postulate: Rules that are accepted without proof.
Axiom: Synonym for postulate.
Theorem: Rules that are proved.
2/14
Geometric Notation
R B
Refers to the NAME of the object (the segment)
RBRB
Refers to the MEASUREMENT of the object (length of the segment)
3/14
Segment Addition Postulate
If B is between A & C, then AB + BC = AC.
If AB + BC = AC, then B is between A & C.
A BC
4/14
Segment Addition PostulateExample #1
A BC
AB = 15 cm
BC = x cm
AC = 41 cm
What is the value of x?
5/14
Segment Addition PostulateExample #2
A BC
AB = x + 5 cm
BC = 2x cm
AC = 29 cm
What is the value of x?
6/14
Segment Addition PostulateExample #3
A BC
AB = x + 10 cm
BC = 24 cm
AC = 3x - 2 cm
What is the length of AB?
7/14
Segment Addition PostulateExample #4
A BC
AB = cm
BC = cm
AC = 18 cm What is the value of x?
1
3x
18
2x
8/14
Where does the Distance Formula come from?
a
bc
2 2( , )x y
1 1( , )x y 2 1( , )x y
2 1( )x x
2 1( )y y
9/14
Distance Formula
2 22 1 2 1( ) ( )AB x x y y
2 2c a b
10/14
Distance Formula
2 22 1 2 1( ) ( )AB x x y y
Find the length of segment AB if the coordinates are E(-3, 3) and F(1, 6).
11/14
Distance Formula
Find the length of segment GH if the coordinates are G(4, -3) and H(-1, 9).
2 22 1 2 1( ) ( )AB x x y y
12/14
Congruent Segments
Congruent Segments: segments that have the same length.
If , then .
If , then .
AB CD
AB CD AB CD
AB CD AB CD
A B
C D
13/14
Homework 1.3
P. 21 4 – 6, 10, 23 – 33, 56
14/14