1. Section 1.2 Points, Lines, and Planes
Chapter 1
Section 1.2
Points, Lines, and Planes

2. To define it or not to define it
Definition: Using known words to define a new word
Undefined terms: When a term is not given a definition
Points, Lines, and Planes are all undefined terms
Mathematicians do not choose to define what they are

3. Undefined terms Point Line Plane Something with no dimension
Something that extends forever in one dimension
Plane
Something that extends forever in two dimensions •

4. Defined Terms Collinear Points Coplanar Points Intersect Intersection
Points that lie on the same line
Coplanar Points
Points that lie in the same plane
Intersect
Two or more geometric figures are said to intersect if they have one or more points in common
Intersection
Set of points the figures have in common

5. Defined Terms Line Segment Ray
A piece of a line cut off by two end points
Ray
All the points on one side of a given point called the initial point
Initial Point

6. Use two points on the line and draw a line above them
Symbolization • A B
Use two points on the line and draw a line above them
Lines
Rays A • B
Use the initial point and any other point on the ray then draw a ray on top
Opposite Rays: Two rays that have the same initial point but extend in opposite directions

7. False
True
False
True
True
True
False
True

8. I E B B C D E A

9. T P P S Q P N N

10. Between A and B
On the same side of P that Q is
Lie on the same line
M is between N and L

12. HW #3 Pg Every Third Problem, 44-51, Even, 68-76, 80, 85, 90 Bring signed Syllabus back