1. Line and Angle Relationships

2. Points, Lines, and Rays
Sometimes it’s necessary to refer to a specific point in space
Points have no size
The only function of a point is to show position
A, read “Point A” A

3. Points, Lines, and Rays
If you draw two points on a sheet of paper, a line can be used to connect them
Lines continue infinitely in both directions while a line segment has 2 endpoints
A B
AB, “line AB”
AB, “line segment AB”

4. Points, Lines, and Rays
A ray is the part of a line that extends without end in one direction
A B C
In AB, “ray AB,” A is the endpoint
The second point that is used to name the ray can be any point other than the endpoint (You could also name it AC)

5. Points, Lines, and Rays Checkpoint
Look at the line below:
A B C
Name a line segment
Name a ray in two different ways
What is the endpoint of ray BC?
AB, AC, BA, BC, CB, and CA
AB and AC or CB and CA
Point B

6. Naming Angles Two different rays with the same endpoint form an angle
The point they have in common is called the vertex of the angle
The rays form the sides of the angle A B C

7. Naming Angles The angle above is made up of BA and BC
Point B is the common endpoint or vertex
When naming an angle we use the angle symbol

8. Naming Angles There are two ways to name an angle
Using the three letters of the points that make up the two rays with the vertex as the middle letter ( ABC, or CBA)
If only given the vertex then use just the letter of the vertex ( B) A B C

9. Naming Angles
When more than one angle is formed by a vertex, you use three letters to name each angle
Since A is the vertex of 3 different angles, each angle needs three letters to name it ( CAD, CAB, and BAD)

10. Naming Angles Checkpoint
Look at the angles formed by the rays below: W X Y Z
Name the vertex
Name all three of the angles
Point Y
XYZ, XYW, and WYZ