Proving two lines are Parallel

Proving two lines are Parallel

by Ashley Barton

What is a proof?

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definition: any kind of valid argument that shows how a statement is true.

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​Different Types of Proofs:

​1.) Paragraph: simply a proof that is written in paragraph form.

2.) Two Column: a list of statements, and the reasons that we know those statements are true.

​3.) Flow Proofs: uses a diagram to show each statement leading to the conclusion.

Angle Relationships:

We can use these angle relationships to determine if two lines are parallel. ​

Angle Relationship

Multiple Choice

Which pair of angles must be supplementary so that r is parallel to s?

• ∠2 and ∠3

• ∠5 and ∠6

• ∠4 and ∠10

• ∠6 and ∠14

Multiple Choice

Line v is a transversal.  Which is a true statement?

• w // x and x // y
• w // x and y // z
• w // y and x // z
• w // z and x // y

Multiple Choice

If ∠5 ≌∠7, which of the following can be concluded?

• r is parallel to s by converse of Alternate Interior Angles Thm.

• u is parallel to v by Converse of Corresponding Angles Thm

• s is ⊥ u by Converse of Alternate Interior Angles Thm

• v ⊥ r by Converse of Alternate Exterior Angles Thm