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Points, Lines, and Line Segments
A Geometry presentation by Olivia Ingram
Points
Points are places on a number line, often
identified by a single dot “•” and are named an
alphabetical letter.
•
A
•
B
Lines
Lines come in three forms:
Ray
•
Line
•
Line Segment
•
•
Measuring Points and Line
Segments
On a number line, you can easily measure the
distance between two points.
0
1
A
B
•
•
2
3
4
5
6
7
Two ways to solve:
•Count the spaces between the points
•Subtract the smallest number from the largest number
4 spaces between points = 4
6–2=4
8
Measuring Points and Line
Segments
You may need to measure line segments whose
points lie on both positive and negative numbers,
which may throw you for a loop, but is just as
simple.
-4
-3
-2
A
B
•
•
-1
When counting, the negative and
positive symbols make no
difference
=2
0
1
2
3
4
Do not solve this by subtraction.
Ignoring the negative and positive
symbols, add the points together:
1+1=2
Measuring Points and Line Segments
Once you know how to measure the distance between points on a line segment,
measuring more than two points on a line segment should be a piece of cake.
Answering Equations
You should write the measurement of the
distance between points using letters and
symbols.
0
1
A
B
•
•
2
3
4
= AB
5
6
7
8
Points, Lines, and Line Segments:
Practice Problems
-4
1
A
B
•
•
-3
2
-2
3
-1
0
1
X
Y
•
•
4
5
6
2
3
4
7
8
9
A
C
•
-4
-3
-2
•
-1
0
•
1
2
3
4
Points, Lines, and Line Segments:
Practice Problem Answers
1) AB = 5
2) XY = 2
3) AC = 5