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Learn about parallel lines, transversals, and the different types of angles formed by them. Use given information and reasoning to complete proofs.
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________________ PARALLEL LINES, TRANSVERSALS AND SPECIAL ANGLES Section 3-1, 3-2
Use the diagram and the given information to complete the missing steps and reasons in the proof. GIVEN: LK = 5, JK = 5, JK ≅ JL PROVE: LK ≅ JL ________ ________ 3. LK = JK 4. JK ≅ JL 5. __________ Bell work 9-30 • Given • Given • Transitive Property 5. Transitive Property
A Line That Intersects 2 Or More Lines At Different Points Is Called A Transversal transversal
3 1 5 7 4 2 6 8 When This Happens, 8 Angles Are Formed
5 1 3 7 4 6 8 2 This Forms 2 Neighborhoods
Remember Vertical And Linear Angles Vertical 3 7 5 1 4 6 8 2
Linear Pairs 3 7 5 1 4 6 8 2
5 1 3 7 4 6 8 2 These Angles Are Called Consecutive Or Same Side Angles
5 3 4 6 1 7 8 2 Interior Angles (Between 2 lines) Exterior Angles (outside the lines)
Alternate Angles Are On Different Sides Of The Transversal And From Different Neighborhoods Alternate Exterior Angles 1 And 8 Angles 2 And 7 Alternate Interior Angles 3 And 6 Angles 4 And 5 5 1 3 7 4 6 8 2
Consecutive Int Angles 3 and 5 Angles 4 and 6 5 3 4 6 Consecutive Ext Angles 1 and 7 Angles 2 and 8 1 7 8 2
3 7 5 1 4 6 8 2 Corresponding Angles Are Located In The Same Position In Each Neighborhood
12 11 14 13 15 16 17 18 Name The Angles • 11 and 15 • 12 and 16 • 13 and 16 • 12 and 18 • 14 and 16 • 14 and 18 • 11 and 14 • 15 and 17
Check Your Answers • Corresponding • Corresponding • Alt Interior • Consecutive (SS) Exterior • Consecutive (SS) Interior • Corresponding • Vertical • Linear
Name the angles • 1 and 3 • 7 and 12 • 11 and 14 • 6 and 10 • 13 and 5 • 9 and 6 • 1 and 13 • 5 and 4 • 7 and 11 • 6 and 11 4 3 2 1 8 7 6 5 12 11 10 9 16 15 14 13 With This Diagram, We Can Work With Angles In Different Neighborhoods As Long As They Are Connected By A Transversal
Check Your Answers • Corresponding • Alt. Int. • Alt. Int. • Cons. (SS) Int. • Corresponding • Alt. Int. • Consecutive Ext • Alt. Ext • Cons. (SS) Int. • None
Parallel lines Lines that are coplanar and do not intersect
If 2 Parallel Lines Are Cut By A Transversal Then: Corresponding Angles Are Congruent Alternate Interior Angles Are Congruent Same Side Interior Angles Are Supplementary
Remember ……… Even Without Parallel Lines Vertical Angles Are Always Congruent Linear Pairs Are Always Supplementary
a b 1 2 a 3 4 6 5 b 8 7 m 1 = 105 • Find: • 3 = • 6 = • 7 = • 4 = • 5 = 75 75 75 105 105
a b 2x+6 4x+25 5x-20 3x-10 2x-10