1. G1
Point, Line, Plane
Point, Line, Plane

2. Geometry Terms
Undefined terms: words that do not have a formal definition but there is agreement about what they mean.
Defined terms: Terms that can be described using known words
Postulate or Axiom: Rule that is accepted without proof.
Theorem: Rule that can be proved.

3. Points Points do not have actual size. How to Sketch: Using dots
How to label:
Use capital letters
Never name two points with the same letter
(in the same sketch). A B C A

4. Lines
Lines extend indefinitely and have no thickness or width.
How to sketch : using arrows at both ends.
How to name: 2 ways
(1) small script letter – line n
(2) any two points on the line -
Never name a line using three points - n A B C

5. Collinear Points
Collinear points are points that lie on the same line. (The line does not have to be visible.) A B C
Collinear C A B
Non collinear

6. Ray Definition: RA : Has one end point and in other direction
carries on forever more
How to sketch:
How to name:
( the symbol RA is read as “ray RA” )

7. Opposite Rays Definition:
Opposite rays are created when three points are collinear
The two rays have the same “endpoint”
and can be viewed as a line.
opposite rays
not opposite rays
The end point will be between the two other points and we write
X – A - Y

8. Segment
Definition:
Part of a line that consists of two points called the endpoints and all points between them.
How to sketch:
How to name:
AB (without a symbol) means the length of the segment or the distance between points A and B.

9. The Segment Addition Postulate
If C is between A and B, then AC + CB = AB.
Example:
AB = AC + CB
Lesson 1-2: Segments and Rays

10. The Segment Addition Postulate
If C is between A and B, then AC + CB = AB.
Example:
If AC = x , CB = 2x and AB = 12, then, find x, AC and CB. 2x x 12
Step 1: Draw a figure
Step 2: Label fig. with given info.
AC + CB = AB
x x = 12
3x = 12
x = 4
Step 3: Write an equation
x = 4
AC = 4
CB = 8
Step 4: Solve and find all the answers

11. Planes
A plane is a flat surface that extends indefinitely in all directions.
How to sketch: Use a parallelogram (four sided figure)
How to name: 2 ways
(1) Capital script letter – Plane M
(2) Any 3 non collinear points in the plane - Plane: ABC/ ACB / BAC / BCA / CAB / CBA A M B C
Horizontal Plane
Vertical Plane
Other

12. Different planes in a figure:B
Plane ABCD
Plane EFGH
Plane BCGF
Plane ADHE
Plane ABFE
Plane CDHG
Etc. D C E F H G

13. Coplanar Objects
Coplanar objects (points, lines, etc.) are objects that lie on the same plane. The plane does not have to be visible.
Are the following points coplanar?
A, B, C ?
Yes
A, B, C, F ? No
H, G, F, E ?
Yes
E, H, C, B ?
Yes
A, G, F ?
Yes
C, B, F, H ? No

14. Intersection of Figures
The intersection of two figures is the set of points that are common in both figures.
The intersection of two different lines is a point. m
Line m and line n intersect at point P. P n
Continued…….

15. 2 Possibilities of Intersection of a Line and a Plane
(1) Line passes through plane – intersection is a point.
(2) Line lies on the plane - intersection is a line.

16. Intersection of Two Different Planes is a Line.B P A R
Plane P and Plane R intersect at the line

17. Lesson 1-1 Point, Line, Plane
Homework
p. 5 #1,5, 9,10,17
p. 12 #8,10,12, 29
Lesson 1-1 Point, Line, Plane