1. 1-1 Points, Lines, & Planes
Geometry

2. What is a definition? Known words used to describe a new word
Undefined terms – not formally defined
There are 3 in geometry.
Point Line Plane

3. Point 1. Has no __________ (no length, width, thickness)
2. Usually represented by a ________
3. Named using one _________ letter B

4. Line Extends _______ in one _________ (length)
Has an _____________ on each end representing the fact that it goes on forever
Consists of an _______ amount of points
Always ___________
Named with a _________ script letter or by ____points on the line
Can be called:
Line l
Line AB or AB
Line BA or BA l A B

5. Plane Extends forever in ____ dimensions (length & width)
A _____ surface consisting of infinitely many points
Usually represented by a _____sided figure
Named with a ________ script letter or ______ points on the surface of the plane
Can be named:
Plane W
Plane ABC, plane BCA, plane CBA, etc. A W C B

6. More Definitions Collinear points – points that lie on the same line
Coplanar points –
points that lie on the same plane

7. 1a Name three points that are collinear.
Naming Collinear and Coplanar Points
1a Name three points that are collinear. G H F E D
1b Name four points that are coplanar.
1c Name three points that are not collinear.
SOLUTION • • •

8. Line Segment (or segment)
A section of a line that has 2 endpoints
Named by its endpoints. AB or BA A B

9. Ray
Piece of a ______ with only one endpoint (initial point) and continues ________ in the other direction
Named by the _________ and a _______ point named on the ray. (name MUST begin with the endpoint!) AB A B

10. Opposite Rays
2 rays that share a common initial point and face opposite directions.
QP and QS are opposite rays. P Q S

11. Example 2: 2a)Draw & label points A & B. 2b)Draw & label points C & D.
2c)Draw AB.
2d)Draw BC.
2e)Draw AC.
2f)Draw DA.

12. Intersect –
2 or more figures intersect if they have one or more points in _______.
Intersection –
all points or sets of points the figures have in _________.
Ex. 3)What is the intersection of:
AB & DA ________
BC & AC ________
ABC & BCD ________
When 2 planes intersect, their intersection is a ______.

15. • Name three points that are collinear.
Naming Collinear and Coplanar Points
• Name three points that are collinear. G H F E D
• Name four points that are coplanar.
• Name three points that are not collinear.
SOLUTION
• Points D, E, F lie on the same line, so they are collinear.
• Points D, E, F, and G lie on the same plane, so they are coplanar.
Also, D, E, F, and H are coplanar.
• There are many correct answers. For instance, points H, E, and G do
not lie on the same line.

16. Assignment