Proof Justifications

• Def of Congruent Segments

• Definition of Linear Pair

• Definition of Bisect

• Definition of Midpoint

• Definition of Congruent Segments

• Congruent Segment Property

• Definition of Bisect

• Definition of Midpoint

• Def. of Congruent Segments

• Segment Addition Property

• Def. of Bisect

• Def. of Midpoint

• Def of Congruent Segments

• Segment Addison Property

• Congruent Segment Property

• Def of Midpoint

Given: <DAY and <YAK are a linear pair.

Conclusion: <DAY and <YAK are supplementary.

WHY?

• Def of Congruent Angles

• Def of Supplementary Angles

• Def of Vertical Angles

• Def of Linear Pair

• Def of Congruent Angles

• Def of Supplementary Angles

• Def of Vertical Angles

• Def of Linear Pair

• Def of Congruent Angles

• Def of Supplementary Angles

• Angle Addition Postulate

• Def of Linear Pair

• Def of Congruent Angles

• Def of Supplementary Angles

• Angle Addition Postulate

• Def of Complementary Angles

• Def of Congruent Angles

• Def of Supplementary Angles

• Def of Vertical angles

• Def of Complementary Angles

Given the picture

Conclusion: <8 and <9 are vertical

WHY?

• Def of Congruent Angles

• Def of Supplementary Angles

• Def of Vertical Angles

• Def of Complementary Angles