Download Measuring Segments.notebook

Measuring Segments.notebook
September 07, 2012
1
Measuring Segments.notebook
September 07, 2012
Sect 1­2: Measuring Segments
Postulate 1­2­1: The points on a line can be put into a one­to­one correspondence with the real numbers.
Distance from A to B is length from point A to point B or from B to A. Distance is always positive.
Length of AB is denoted AB.
AB => segment => object
AB => length => number
2
Measuring Segments.notebook
September 07, 2012
On a number line to find the distance between two points, A and B.
|a ­ b| or |b ­ a| == since you take the absolute value, order doesn't matter.
­10
­9
­8
­7
­6
­5 ­4
­3
­2
­1
0
1
2
3
4
5
6
7
8
9
10
Congruent segments : two segments that are the same length.
A
B
Q
R
AB ≅ QR segment AB is congruent to segment QR AB = QR
length of AB is equal to length of QR
3
Measuring Segments.notebook
September 07, 2012
Segment Addition Postulate:
If B is between A and C, then AB + BC = AC
Example: G is between F and H. FG = 6, FH = 11
Find GH.
Example: M is between N and O. NM = 17, MO = 3x­5, and NO = 5x + 2. Find the measure of each segment.
4
Measuring Segments.notebook
September 07, 2012
If the point is exactly halfway between the two endpoints, it is called the midpoint.
The midpoint of AB is the point that bisects or divides the segment into two congruent segments.
Does a line have a midpoint?
Segment bisector: ray, segment or line that intersects a segment at its midpoint.
5