1. Section 3.1 ~ Parallel and Skew lines!
Be able to identify angle pairs (corresponding, alternate interior, same-side interior, alternate exterior, same-side exterior)!
Quick Definitions:
Parallel lines: coplanar lines that do not intersect
Parallel planes: planes that do not intersect
Skew lines: noncoplanar lines that do not intersect

2. A transversal is a _____ that intersects two other ______!
line
A transversal is a _____ that intersects two other ______!
lines t
In this picture, line ____ is the transversal. 1 2 3 4 n 8 5
This transversal creates ____ angles! 6 7 8 m
Pairs of these angles have special names, depending on their positions. t

3. Identify the transversal(s) in each picture:b c k m n r s t p
line m
line b
lines s, t, p, r

4. Special Angle Pairs in Parallel Lines Cut by a Transversal:
Picture:
Relationship:
Corresponding Angles
Alternate Interior Angles
Consecutive Interior Angles
Alternate Exterior Angles
Consecutive Exterior Angles
congruent
congruent
supplementary
congruent
supplementary

5. Practice Identifying the Special Angle Pairs:
Corresponding Angles
Alternate Interior Angles
Consecutive Interior Angles
Alternate Exterior Angles
Consecutive Exterior Angles
1 & 5, 4 & 8, 2 & 6,
3 & 7, 1 & 9, 2 & 10,
4 & 12, 3 & 11 1 2 3 4 5 6 7 8 9 10 11 12
4 & 6, 3 & 5,
2 & 12, 3 & 9
4 & 5, 3 & 6,
2 & 9, 3 & 12
1 & 7, 2 & 8,
1 & 11, 4 & 10
1 & 8, 2 & 7,
1 & 10, 4 & 11

6. Use the picture to complete each statement:50
If m5 = 130, then m8 =____ because they are… 1 2 3 4 5 6 7 8 9 10 11 12
supplementary
125
If m4 = 125, then m6 =____ because they are…
alternate interior
125
If m4 = 125, then m8 =____ because they are…
corresponding
135
If m2 = 45, then m7 =____ because they are…
consecutive ext
130
If m3 = 50, then m6 =____ because they are…
consecutive int 42
If m7 = 42, then m1 =____ because they are…
alternate ext

7. MORE PRACTICE: Use the picture to complete each statement.50
If m5 = 130, then m4 =____ because they are… 1 2 3 4 5 6 7 8 9 10 11 12
same-side interior 25
If m5 = 25, then m3 =____ because they are…
alternate interior
125
If m5 = 125, then m1 =____ because they are…
corresponding
130
If m1 = 50, then m8 =____ because they are…
same-side ext
130
If m3 = 50, then m2 =____ because they are…
supplementary 51
If m2 = 51, then m8 =____ because they are…
alternate ext

8. Find the value of each variable.2x
2x + 60
x + 60
3x - 20
2x + 2x + 60 = 180
3x - 20 = x + 60
4x + 60 = 180
2x - 20 = 60
4x = 120
2x = 80
x = 30
x = 40

9. Your Turn!
60° 3y
3y + 60 = 180
3y = 120
y = 40