1. Geometry Chapter 1 Section 2
1-2 Points, Lines, & Planes
Geometry
Chapter 1 Section 2
Points, Lines, & Planes

2. Point Undefined term in geometry
Undefined term in geometry
Represents the simplest geometric concept
It is a location in space (indicates position).
All geometric figures consist of points.
Represented as a dot

3. Points - graphically A D B C . ● ● ● ●

4. Line Undefined term in geometry
Undefined term in geometry
Consists of an infinite number of points
Extends in opposite directions
Goes on FOREVER

5. Identifying & Representing Lines
The minimum number of points needed to identify a line is two.
A way we represent the above line is… ● B ● l A l

6. Points & lines If all of the points lie on the same line,
If all of the points lie on the same line,
then the points are collinear.
If all of the points don’t lie on the same line,
then the points are non-collinear.

7. Plane Undefined term in geometry Sort of like a flat geometric “wall”
Undefined term in geometry
Sort of like a flat geometric “wall”
“2 dimensional”
Consisting of an infinite number of points
Infinite in size

8. Identifying & Representing Planes
The minimum number of points needed
to identify a plane is 3.
A way to represent a plane is…
P (pick a capital letter) or
ABC (3 non-collinear points…use capital letters) B A P C

9. Points & Planes If all of the points lie in the same plane,
If all of the points lie in the same plane,
then the points are coplanar.
If all of the points don’t lie on the same plane,
then the points are non-coplanar.

10. Dashes in diagrams indicates parts hidden from view in figures in space. A Q P B R S C N

11. Intersection
The intersection of two figures is the set of points that are in both figures.

12. True or False? P is in M b is in M YX contains P M contains XY
A is on b
A & P are in M
N contains P
A & P are collinear A X Y N M P b

13. Section 1.2 Written Exercises
Homework:
Section 1.2 Written Exercises
(p. 7-9) #1-18 & 27-31