1. PARALLEL LINES CUT BY A TRANSVERSAL

2. DEFINITIONS PARALLEL TRANSVERSAL ANGLE VERTICAL ANGLE
CORRESPONDING ANGLE
ALTERNATE INTERIOR ANGLE
ALTERNATE EXTERIOR ANGLE

3. DEFINITIONS
SUPPLEMENTARY ANGLE
COMPLEMENTARY ANGLE
CONGRUENT

4. Parallel lines cut by a transversal2 1 3 4 6 5 7 8

5. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 1 and < 2 are called SUPLEMENTARY ANGLES
They form a straight angle measuring 180 degrees.

6. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 2 and < 3
< 3 and < 4
< 4 and < 1
< 5 and < 6
Name other supplementary pairs:
< 6 and < 7
< 7 and < 8
< 8 and < 5

7. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 1 and < 3 are called VERTICAL ANGLES
They are congruent m<1 = m<3

8. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 2 and < 4
< 6 and < 8
Name other vertical pairs:
< 5 and < 7

9. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 1 and < 5 are called CORRESPONDING ANGLES
They are congruent m<1 = m<5
Corresponding angles occupy the same position on the top and bottom parallel lines.

10. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 2 and < 6
< 3 and < 7
Name other corresponding pairs:
< 4 and < 8

11. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 4 and < 6 are called ALTERNATE INTERIOR ANGLES
They are congruent m<4 = m<6
Alternate Interior on on the inside of the two parallel lines and on opposite sides of the transversal.

12. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 3 and < 5
Name other alternate interior pairs:

13. Parallel lines cut by a transversal2 1 3 4 6 5 7 8
< 2 and < 8
< 1 and < 7
Name other alternate exterior pairs:

14. TRY IT OUT 2 1 3 4 6 5 7 8 120 degrees The m < 1 is 60 degrees.
What is the m<2 ?
120 degrees

15. TRY IT OUT 2 1 3 4 6 5 7 8 60 degrees The m < 1 is 60 degrees.
What is the m<5 ?
60 degrees

16. TRY IT OUT 2 1 3 4 6 5 7 8 60 degrees The m < 1 is 60 degrees.
What is the m<3 ?
60 degrees

17. TRY IT OUT
120 60 60
120
120 60 60
120

18. TRY IT OUT 2x + 20 x + 10 What do you know about the angles?
Write the equation.
Solve for x.
SUPPLEMENTARY
2x x + 10 = 180
3x + 30 = 180
3x = 150
x = 30

19. TRY IT OUT 3x - 120 2x - 60 What do you know about the angles?
Write the equation.
Solve for x.
ALTERNATE INTERIOR
3x = 2x - 60
x =
Subtract 2x from both sides
Add 120 to both sides

20. WEBSITES FOR PRACTICE Ask Dr. Math: Corresponding /Alternate Angles
Project Interactive: Parallel Lines cut by Transversal