1. Cell phone use is prohibited.
Students:
Today is a red light day.
Cell phone use is prohibited.
This is your warning.

2. 4.01 Points, Lines, and Planes

3. A point is a exact location in space. It has no dimension.
A point is represented by a small dot.
The notation used to represent a point is a capital letter or using the word point.
Examples: A
Point B
Collinear points are points that lie on the same line.
Points A , B , and C
are collinear.
A B C

4. A line has one dimension.
A line is a set of infinite points that extends without end in two directions.
A line has one dimension.
A line is represented two dots with a line drawn through them with arrowheads. m
A B
The notation used to represent a line is either a small cursive letter or two capital letters with a line on top of them. or
Line m

5. A line segment is part of a line. It has a beginning and end.
The beginning and end points are endpoints.
A B
Point A and Point B are the endpoints.
The notation used to represent a line segment is two capital letters with a bar on top of them. or
Important:
Notice that
is not the same as

6. It has a starting point and no ending point.
A ray is part of a line.
It has a starting point and no ending point.
The starting point is the endpoint of the ray.
A B
The notation used to represent a ray is two capital letters with a arrow pointing right on top of them.
The endpoint must always be the first letter.
Point A is an endpoint.
Point B is an endpoint.
Important:
Since rays are directional
is not the same as

7. A plane is a flat surface that has two dimensions and extends in all directions without end.
A B
P C
The notation used to represent a plane is using the word Plane and one cursive capital letter or the word plane with three capital letters.
Plane P or
Plane ABC
Coplanar points are points that lie on the same plane.
Coplanar lines are lines that lie on the same plane.

8. Use the diagram at the right.
Name any 2 points. A
B C
R D
A or B or C or D
Name any line.
Name any line segment.
Name 3 collinear points.
A , B , and C
Name any ray.
Name the plane.
Plane R or Plane ABD