3.3 Paragraph and Flow Proofs

Warm-up (IN)

Learning Objective: to write and understand mathematical proofs and to use mathematical reasoning to prove that a

statement is always true.

Give the reason for the following statements.

Segment addition postulate

Def of bisector

Def. of

Property of Quads

1. If point X is between points P and Q, then PX+XQ=PQ.

2. The sum of the measure of the exterior angles of any quadrilateral is 360º.

3. If AB=KL, then KLAB

4. . then , bisects If XACBAXBACAX

Notes

Theorem - A conjecture that can be proved to be true

Paragraph Proof - Writing your statements and reasons in a paragraph

Exploration p. 125Exterior Angle Theorem

-

3

12

4

The measure of an exterior angle of a triangle is equal to the sum of the 2 remote interior angles

214 mmm

Ex 1 – Write a paragraph proof of the exterior angles thm.

3

12

4

Given:

angleexterior an is 4 triangleain

anglesinterior are 3,2,1

Prove: 214 mmm

CKC p. 126

Flow Proof - A method that shows the relationships between the statements in a proof

Ex 2 – Write a flow proof to show that

654 Given: Prove:

65

then ,18064 if

mm

mm

18064 mm65 mm

HW – p. 127-129 #1-6,10-19,22-26

Out – Which type of proof do you like best? Why?

Summary – I was surprised…

Or

I realized…

POW!!