1. Chapter 1 Exploring Geometry: Points, Lines, and Angles in the Plane
Section 1
Points and Lines in the Plane
Objectives:
Students will be able to identify and model endpoints, line segments, lines, rays and collinear points.
Chapter 1
Section 1 - Points and Lines in the Plane

2. Section 1 - Points and Lines in the Plane
A point represents a location.
A point has no size and is represented by a dot.
A point is named by an uppercase letter. A B
Points A and B.
Chapter 1
Section 1 - Points and Lines in the Plane

3. Section 1 - Points and Lines in the Plane
A line is made up of an infinite number of points, and extends endlessly in opposite directions.
A line can be named by two points on the line
or by a single lowercase script letter. l
or Line l.
Line AB, BA, A B
Chapter 1
Section 1 - Points and Lines in the Plane

4. Section 1 - Points and Lines in the Plane
Example 1
Name the line in seven different ways. m L K J
Answer: The line can be named as line m.
There are three points on the line. Any two of the points can be used to name the line.
JK, JL, KJ, KL, LJ, LK
Chapter 1
Section 1 - Points and Lines in the Plane

5. Section 1 - Points and Lines in the Plane
Collinear
Points that lie on the same line are called collinear.
collinear points
noncollinear points
Chapter 1
Section 1 - Points and Lines in the Plane

6. Section 1 - Points and Lines in the Plane
Example 2
Which three points are collinear? E G F A D C B H
Answer: Points A, D, and F are collinear.
Chapter 1
Section 1 - Points and Lines in the Plane

7. Section 1 - Points and Lines in the Plane
A plane is a flat surface, with no thickness, that extends in all directions without end.
A plane can be named by three noncollinear points,
or by a single capital
script letter. P
or Plane P.
Plane ABC C B A
Chapter 1
Section 1 - Points and Lines in the Plane

8. Section 1 - Points and Lines in the Plane
Line Segment
A line segment is part of a line that has a fixed length. It consists of two endpoints and all points between them.
A segment is named by its endpoints. B A
Segment AB or
Segment BA
Chapter 1
Section 1 - Points and Lines in the Plane

9. Section 1 - Points and Lines in the Plane
Example 3
Draw and name all of the line segments between points A, B, and C. A B C
Segment AB, AC, and BC.
Chapter 1
Section 1 - Points and Lines in the Plane

10. Section 1 - Points and Lines in the Plane
Ray
A ray is a part of a line that has one endpoint and extends endlessly in one direction.
A ray is named by its endpoint and one other point on the ray. A B C AB AC
Read: Ray AB or Ray AC.
Chapter 1
Section 1 - Points and Lines in the Plane