1. 1.1 – Identify Points, Lines, and Planes
Geometry Chapter 1
1.1 – Identify Points, Lines, and Planes

2. Geometry Vocabulary
Objective: Students will be able to apply geometric vocabulary by identifying and correctly writing terms.
Agenda
Undefined Terms (w/practice)
Defined Terms (w/practice)
Intersections

3. Undefined terms
In geometry, the words point, line, and plane are known as undefined terms.
These words do not have formal definitions, but there is an agreement about what they mean.

4. Homework
Textbook Pg. 5
#’s 1-26 (Except #2)

5. Point A Definition (of sorts): Has no dimension; represented by a dot.
Picture/Paraphrase: Point A
Knowledge Connection: What are some examples of Points in the real world? A

6. Line *Through any two points, there exists a line.
Definition (of sorts): Has one dimension; represented by a line with two arrowheads, extending without end.
Picture/Paraphrase:
Knowledge Connection: What are some examples of a Lines in the real world?
Line AB ( 𝑨𝑩 ) Or
Line l l A B

7. Planes *Through any three points not on a line, there exists a plane.
Definition (of sorts): Has two dimensions; represented by a shape that looks like a floor or a wall, and extends without end.
Picture/Paraphrase:
Knowledge Connection: What are some examples of a Planes in the real world? M A B C
Plane ABC Or
Plane M

8. Collinear Points Definition: Points that all lie on the same line.
Picture/Paraphrase:
Knowledge Connection: What are some examples of a collinear points in the real world?
Points A, B, and C are Collinear:
Points A, B, and D are NonCollinear: A B C D

9. Coplanar Points Definition: Points that all lie in the same plane.
Picture/Paraphrase:
Knowledge Connection: What are some examples of a coplanar points in the real world?
Points A, B, C, and D are Coplanar:
Points A, B, C, and M are NonCoplanar: D A B C M

10. Example 1: Use the diagram on page 3 of the textbook to answer the questions
a. ) Give two other names for 𝑷𝑸 and plane R.
b.) Name three points that are collinear and four points that are coplanar. R V S P m T n Q
Ans: 𝑸𝑷 and Line n; Plane SVP and Plane SVT
Ans: Points S, P, and T are Collinear.
Ans: Points S, P, T, and V are Coplanar

11. Defined terms
In geometry, terms that can be described using known words such as point or line are defined terms.

12. Segment
Definition: A finite portion of a line, consisting of two endpoints.
Picture/Paraphrase: Line segment AB; 𝑨𝑩
Knowledge Connection: What are some examples of Segments in the real world? A B

13. Ray
Definition: A portion of a line that contains one endpoint, and extends without end in one direction.
Picture/Paraphrase: Ray AB, 𝑨𝑩
Knowledge Connection: What are some examples of Rays in the real world? A B

14. Opposite Rays
Definition: Rays that have the same endpoint, but extend in opposite directions.
Picture/Paraphrase: If point C lies on 𝑨𝑩 between A and B, then 𝑪𝑨 and 𝑪𝑩
Knowledge Connection: What are some examples of Opposite Rays in the real world? A B C

15. Example 2: Use the diagram on page 4 of the textbook to answer the questions
a. ) Give another name for 𝐺𝐻 .
b.) Name all the rays with endpoint J. which of these are opposites rays? G F J H E
Ans: 𝑯𝑮
Rays with endpoint J:
𝑱𝑬 , 𝑱𝑭 , 𝑱𝑮 , 𝑱𝑯
Opposite Rays:
𝑱𝑬 and 𝑱𝑭
𝑱𝑮 and 𝑱𝑯

16. Intersection
The intersection of two or more geometric figures is the set of points the figures have in common.
Examples of intersection:
1.) The intersection of two different lines is a point.
2.) The intersection of two different planes is a line. m n A

17. Example 4: Use the diagram on page 5 of the textbook to answer the questions
a. ) Name the intersection of 𝑷𝑸 and line k.
b.) Name the intersection of plane A and Plane B.
c.) Name the intersection of line k and plane A.
Ans: Point M
Ans: Line k
Ans: Line k