Chapter 2.5 Proving Angles
Congruent
Bell Work
• If you get an A, then you’ll get money
• 1) Amanda got a 95% in science
– Conclusion:
• 2) Amanda got $100 from grandma
– Conclusion:
• 3) If you are fit, then you are hot
• If you are hot, then you will get a lot of dates
– Conclusion:
Vocabulary
• Complementary Angle = two angles that add
up to 90 (right angle)
• Supplementary Angle = two angles that add
up to 180 (straight line)
• Theorem = A theorem is a conjecture that is
proven
Vocabulary
• Paragraph proof = Proof written in paragraph
form
Vertical Angles Theorem
• Vertical angles are congruent
1  3
2  4
Example
• Which are vertical angles?
Congruent Supplements Theorem
• If two angles are supplements of the same
angle (or of congruent angles), then the two
angles are congruent
Congruent Complements Theorem
• If two angles are complements of the same
angle (or of congruent angles), then the two
angles are congruent
• All right angles are congruent
• If two angles are congruent and
supplementary, then each is a right angle
Solving Example with Vertical
Angles
Solving Example with
Supplementary Angle
Solving Example with
Complementary Angle
Solving problem with combination
of vertical and supplementary
Activity (5 min)
• Write the summary about this section in your
Cornell note.
• Some questions to consider:
– What is the topic about?
– What did I learn from this lesson?
– What questions do I have?
– How does it relate to other lessons/real life?
Classwork
• P 112 #1-6, 12, 13, 30-32
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Chapter 2.5 Geometry