Proofs with Parallel Lines

Given: k // p. Which of the following in NOT a valid proof that m∠1 + m∠6 = 180°?

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• Def Alt Ext Angles
• Alt Ext Angle Thm
• Alt Ext Angle Convese

• Def of Corr Angles
• Corr Angle Postulate
• Corr Angle Convese
• S-S Int Thm

• Def of Supplementary Angles
• Def of Linear Pair
• Linear Pair Postulate
• Congruent Supplements Thm

• Alt Int Angle Post
• Alt Int Angle Definition
• Alt Int Angle Thm
• Alt Int Angle Converse

What is Reason 1

• Alternate Exterior Angles Theorem
• Corresponding Angles Theorem
• Given 

What is the reason for step 2

• Alternate Exterior Angles Theorem
• Same Side Interior Angles Thereom
• Definition of Congruence

What is the reason for step 3

• Alternate Exterior Angles Theorem
• Converse of Alternate Exterior Angles
• Alternate Interior Angles Theorem 
• Converse of Alternate Interior Angles

What is the reason for step 4

• Corresponding Angles Theorem
• Vertical Angles Theorem
• Alternate Interior Angles Theorem
• Converse of Alternate Interior Angles

Which is the correct reason for statements 2 and 4 in the proof?

• Corresponding Angles
• Substitution
• Definition of Congruent Angles
• Vertical Angles are congruent.