Segments and Their Measures

1
Section 1-3

• Segments and Their Measures

2
Postulates or Axioms

• Rules that are accepted without proof.

3
Ruler Postulate

• Points on a line can be matched 1 to 1 with real
  numbers called coordinates.
• The distance between points A and B, AB, is the
  absolute value of the difference between the
  coordinates.

Distance of AB ABl5-3l2

• AB is called the length of AB

4
Example 1

• Draw a segment on your paper.
• Using the metric side of your ruler, measure the
  length of the segment in centimeters.

5
Segment Addition Postulate

• If B is between A C, then AB BC AC
• If AB BC AC, then B is between A C

6
Example 2

• Draw a sketch of 3 collinear points and write the
  segment addition postulate for them.

M is between H and A
7
Answer
HM MA HA
8
Example 3

• Suppose J is between H and K. Use the segment
  addition postulate to solve for x.

HJ 5x 3 JK 8x-9 HK 131
9
Example 4

• Suppose M is between L and N. Use the segment
  addition postulate to solve for x. Then find the
  length of LM and MN.

LM 3x 8 MN 2x 5 LN 23
10
Example 5
Given PT 20 QS 6 PQ
QR RS
Find the following QR_____ RS_____ PQ_____ ST
_____ RP_____ RT_____ SP_____ QT_____