1. Undefined Terms: Point, Line, Plane, & Space Module A1-Lesson 1

2. Definition A statement of the meaning of a term (word, phrase, or set of symbols)

3. Undefined Terms Terms that cannot be mathematically defined using other known words – Examples: Point Line Plane Space

4. Point No dimension Represented by a small dot Point A ∙ A

5. Line One Dimension Extends without end in two directions Represented by a line with two arrowheads Line l or BC l B C

6. Plane Two dimensions Represented by a shape that looks like a floor or wall You have to imagine that it extends without end Plane M or Plane DEF M D E F

7. Space The set of all possible points made up in an infinite planes.

8. Postulates Statements that are accepted without further justification

9. Postulate 1: Two Points Determine a Line Words Through any two points there is exactly one line. Symbols Line n passes through points P & Q. P Q n

10. Postulate 2: Three Points Determine a Plane Words Through any three points not on a line there is exactly one plane. Symbols Plane t passes through points A, B, & C. t A B C

11. Collinear Points Points that lie on the same line

12. Coplanar Points Points that lie on the same plane

13. Coplanar Lines Lines that lie on the same plane

14. Line Segment Part of a line that consists of two points, called endpoints And all points on the line that are between the endpoints Represented by a line with no arrowheads A B AB with endpoints A & B

15. Ray The ray AB consists of – The endpoint A – And all the points on line AB that lie on the same side of A as B Represented by a line with one arrowhead A B AB with endpoint A

16. Endpoint A point used to define a line segment or ray. A line segment has two endpoints; a ray has one. Ray