PARALLEL LINES CUT BY A TRANSVERSAL

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```					PARALLEL LINES CUT BY A
TRANSVERSAL
DEFINITIONS
•   PARALLEL
•   TRANSVERSAL
•   ANGLE
•   VERTICAL ANGLE
•   CORRESPONDING ANGLE
•   ALTERNATE INTERIOR ANGLE
•   ALTERNATE EXTERIOR ANGLE
DEFINITIONS
• SUPPLEMENTARY ANGLE
• COMPLEMENTARY ANGLE
• CONGRUENT
Parallel lines cut by a transversal

2       1
3       4
6    5
7 8
Parallel lines cut by a transversal

2       1
3       4
6       5
7 8

< 1 and < 2 are called SUPLEMENTARY ANGLES
They form a straight angle measuring 180 degrees.
Parallel lines cut by a transversal

2       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
Parallel lines cut by a transversal

2       1
3       4
6      5
7 8

< 1 and < 3 are called VERTICAL ANGLES
They are congruent m<1 = m<3
Parallel lines cut by a transversal

2       1
3       4
6     5
7 8
< 2 and < 4

< 6 and < 8

Name other vertical pairs:               < 5 and < 7
Parallel lines cut by a transversal

2       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.
Parallel lines cut by a transversal

2       1
3       4
6       5
7 8
< 2 and < 6

< 3 and < 7

Name other corresponding pairs:           < 4 and < 8
Parallel lines cut by a transversal

2       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.
Parallel lines cut by a transversal

2       1
3       4
6       5
7 8
< 3 and < 5

Name other alternate interior pairs:
Parallel lines cut by a transversal

2       1
3       4
6        5
7 8
< 2 and < 8

Name other alternate exterior pairs:        < 1 and < 7
TRY IT OUT

2       1
3       4
6    5
7 8

The m < 1 is   60 degrees.   120 degrees
What is the m<2 ?
TRY IT OUT

2       1
3       4
6    5
7 8

The m < 1 is   60 degrees.   60 degrees
What is the m<5 ?
TRY IT OUT

2       1
3       4
6    5
7 8

The m < 1 is   60 degrees.   60 degrees
What is the m<3 ?
TRY IT OUT

120 60
60 120
120   60
60 120
TRY IT OUT

2x + 20        x + 10

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

3x - 120
2x - 60

What do you know about the angles? ALTERNATE INTERIOR
Write the equation.                            3x - 120 = 2x - 60
Solve for x.                                        x   =    60
Subtract 2x from both sides
WEBSITES FOR PRACTICE
Ask Dr. Math: Corresponding /Alternate Angles

Project Interactive: Parallel Lines cut by Transversal

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