1. 1-2: Points, Lines and Planes

2. l Undefined Terms P ABC Term Description Name Diagram Point
Indicates location
One capital letter
Has no size
Line
Straight path
Any two points:
Extends in opposite directions or
Has no thickness
One lowercase letter:
Infinitely many points l
Flat surface
One uppercase letter:
Plane
Extends without end P
Has no thickness
Three points not on same line:
Infinitely many lines
ABC

3. Types of Points Collinear: Coplanar: Space:
Two or more points that lie on the same line
Coplanar:
Three or more points that lie on the same plane
Lines on the same plane are coplanar
Space:
Set of all points in three dimensions. A B C C A B D

4. Example 1: What are two other ways name ?
What are two ways to name plane Q?
What are the names of three collinear points?
What are the names of four coplanar points?
line l or
plane AEC
plane ADC
points A, E, D
points A, F, B
points A, E, C
points A, E, B
Complete Got It? #1 p.12
b. plane RVS c. N, Q, T

5. Defined Terms Term Description Name Diagram Segment Part of a line
Two endpoints:
Two endpoints and all points between or
Ray
Part of a line
Endpoint and any point on the ray:
One endpoint and all points on the line on one side of endpoint
Opposite Ray
Two rays that share the same endpoint
Shared endpoint and any other point on each ray:
Form a line

6. Example 2: What are the names of the segments in the figure?
What are the names of the rays in the figure?
Which of the rays in part(b) are opposite rays?
Complete Got It? #2 p.13

7. Postulates (statements assumed to be true)
Through any two points there is exactly one line.
Postulate 1-2
If two distinct lines intersect, then they intersect in exactly one point.
Postulate 1-3
If two distinct planes intersect, then they intersect in exactly one line. A B C D A B G

8. Example 3: What is the intersection of and ?
What is the intersection of plane ABCD and ?
What is the intersection of plane ABGH and plane DCHG? G A
Complete Got It? #3 p.14
a. plane BFE
b. Two planes intersect in one line, so you need two common points to name the common line.

9. Postulate
Postulate 1-4
Through any three noncollinear points there is exactly one plane. C A B D

10. Example 4: Each surface of the box represents part of a plane
Which plane contains points A, B and C?
Which plane contains points E, H and C?
plane ABCD
plane EHCB
a. plane LMNP b.
Complete Got It? #4 p.15

11. Homework: P , #’s 8-22, 40-45