1. Splash Screen

2. Five-Minute Check (over Lesson 2–4) Then/Now New Vocabulary
Postulates: Points, Lines, and Planes
Key Concept: Intersections of Lines and Planes
Example 1: Real-World Example: Identifying Postulates
Example 2: Analyze Statements Using Postulates
Key Concept: The Proof Process
Example 3: Write a Paragraph Proof
Theorem 2.1: Midpoint Theorem
Lesson Menu

3. Identify and use basic postulates about points, lines, and planes.
Write paragraph proofs.
Then/Now

4. postulate axiom proof theorem deductive argument paragraph proof
informal proof
Vocabulary

5. Points, Lines and Planes
Postulate or Axiom
Statement that is accepted as true without proof

6. Concept

7. Concept

8. If plane T contains contains point G, then plane T contains point G.
Analyze Statements Using Postulates
A. Determine whether the following statement is always, sometimes, or never true. Explain.
If plane T contains contains point G, then plane T contains point G.
Answer: Always; Postulate 2.5 states that if two points lie in a plane, then the entire line containing those points lies in the plane.
Example 2

9. contains three noncollinear points.
Analyze Statements Using Postulates
B. Determine whether the following statement is always, sometimes, or never true. Explain.
contains three noncollinear points.
Answer: Never; noncollinear points do not lie on the same line by definition.
Example 2

10. A. Determine whether each statement is always, sometimes, or never true. Plane A and plane B intersect in exactly one point.
A. always
B. sometimes
C. never A B C
Example 2

11. B. Determine whether each statement is always, sometimes, or never true. Point N lies in plane X and point R lies in plane Z. You can draw only one line that contains both points N and R. A B C
A. always
B. sometimes
C. never
Example 2

12. Concept

13. Concept

14. End of the Lesson