1.3 Segments and Their Measures. Objectives/Assignment. Use segment postulates. Use the Distance Formula to measure distances as applied. Using Segment Postulates.
The distance between points A and B written as AB, is the absolute value of the difference between the coordinates of A and B.
AB is also called the length of AB.
Names of points
Coordinates of pointsPostulate 1: Ruler Postulate
AB = |x2 – x1|
Solution: Use a metric ruler. Align one mark of the ruler with A. Then estimate the coordinate of B. For example if you align A with 3, B appears to align with 5.5.
The distance between A and B is about 2.5 cm.Ex. 1: Finding the Distance Between Two Points
AB = |5.5 – 3| = |2.5| = 2.5
Finding the Distance on a Number Line
Find AB, BA, CB, BC, BD, and DB
AB = 1.5, BA = 1.5, CB = 3, BC = 3, BD = 5, DB = 5
Point B is between points A and C.
Point E is NOT between points D and F.
In the diagram, AD = 34, BC = 14, CD = 13 and AB = BE = EC.
Find BE, EC, AB, AE, ED, and BD
Solution: BE = 7, EC = 7, AB = 7, AE = 14, ED = 20, and BD = 27
What is the Distance Formula based on?
| y2 – y1 |
| x2 – x1 |
c2 = a2 + b2
Find the distance between the points X(2, -5) and Y(- 4, - 9)