1. 5.1(a) Notes: Postulates and Paragraph Proofs
Date:
5.1(a) Notes: Postulates and Paragraph Proofs
Lesson Objective: Construct and justify statements about geometric figures, using basic postulates and paragraph proofs.
CCSS: G.MG.3
You will need: a pencil
Real-World App: How is a trellis supported?
This is Jeopardy!!!: This is a sketch of two congruent line segments.

2. Lesson 1: Learning a New Language
Geometry
English
When To Use
AB CD
Segment AB is con-gruent to segment CD.
This is what we are proving
AB = CD
The length of AB equals the length of CD.
Use this in proofs with the properties of =
/ A / B
Angle A is congruent to angle B.
m/ A = m/ B
The measure of / A is equal to the measure of / B.

5. Lesson 2: Identifying Postulates with Mr. Hardesty
Explain how the picture illustrates that each statement is true. Then state the postulate that can be used to show each statement is true.

6. a. Line s contains points F and H. Point C can also be on line s.

7. b. Lines m and t intersect at point A.

8. c. Points A and B lie in the plane of the trellis and on line m
c. Points A and B lie in the plane of the trellis and on line m. Line m lies entirely in the plane of the trellis.

9. d. Points B and H determine a line.

10. Lesson 3: Geometry Lab Recording Sheet

11. 5.1(a): Do I Get It? Yes or No
Explain how the picture illu-
strates that each statement is
true. Then state the postulate
that can be used to show each
statement is true.
Line m contains points F and
G. Point E can also be on line m.
Lines s and t intersect at
point D.
3. Planes P and Q intersect in line m.

12. 5.1(a): Do I Get It? Continued
Determine whether each statement is always, sometimes, or never true. Explain.
If 2 coplanar lines intersect, then the point of intersection lies in the same plane as the 2 lines.
Four points are collinear.
Two intersecting lines determine a plane.