1. 2.4: Special Angles on Parallel Lines
WELCOME
2.4: Special Angles on Parallel Lines
Last Night’s Homework:
Tonight’s Homework:

2. Warm-Up
Solve for x: Solve for x:
𝟏 𝟒 +𝟓𝒙= 𝒙 𝟑 80
2x+60

3. Chapter 2 Section 4

9. Transversal line
Line that intersects “crosses” two or more coplanar lines J K L
“J is transversal of K & L”

10. Transversal lines and their angles
Corresponding:
Occupy the same position
Alternate Exterior:
Outside and Opposite sides 1 3 2 4
Alternate Interior:
Inside and Opposite sides
Same Side Interior:
Inside and same sides 7 5 6 8

12. Corresponding Angles ∠1 ≌ ∠2
If two ‖ lines are cut by a transversal, then corresponding angles are congruent 1 2
∠1 ≌ ∠2

13. Alternate Exterior ∠ ∠7 ≌ ∠8
If two ‖ lines are cut by a transversal, then alternate exterior angles are congruent 7 8
∠7 ≌ ∠8

14. Alternate Interior ∠ ∠3 ≌ ∠4
If two ‖ lines are cut by a transversal, then alternate interior angles are congruent 3 4
∠3 ≌ ∠4

15. Same Side Interior ∠ ∠5 + ∠6 = 180°
If two ‖ lines are cut by a transversal, then the two same side interior angles are supp. (180°) 5 6
∠5 + ∠6 = 180°

16. Biconditional ǁ line Relationship
Corresponding :
Occupy the same position
Alternate Exterior :
Outside and Opposite sides 1 3
≌ iff ‖
≌ iff ‖ 2 4
Alternate Interior :
Inside and Opposite sides
Same Side Interior :
Inside and same sides 7 5
≌ iff ‖
Supp. iff ‖ 6 8

18. Perpendicular Transversal
If a transversal is perpendicular to one of two ‖ lines, then it is perpendicular to the other line J K L
K ⊥ L

19. Practice: