1. Parallel lines
Section 3-1

2. 3 line relationships
Parallel lines – coplanar lines that never intersect
Intersecting lines – coplanar lines that share one point
Skew lines – noncoplanar lines

3. 2 more items
Parallel planes – 2 planes that never intersect (spacing remains even)
A line and a plane are parallel – if they never intersect

4. Theorem 3-1
If 2 parallel planes are cut by a third plane, then the lines of intersection will be parallel
If the first two planes are parallel, then the red lines are parallel.

5. Transversals
Transversal – a line that intersects two or more coplanar lines in different points 1 2
A transversal is a route from one line to another 4 3 5 6 7 8
When two lines are cut by a transversal, there are 8 angles formed

6. Interior and Exterior Angles
Interior angles – the angles between the two lines
Exterior angles – the angles outside the two lines 1 2 4 3 5 6 8 7

7. Angle Pairs with Two Lines Cut by a Transversal1 2 4 3
When we refer to an angle pair, we will use one angle from each of the two lines being cut by the transversal
One from here
And one from here 5 6 8 7

8. Corresponding Angles
Lie in the same position with regard to the lines and the transversal.
2, 6
1, 5
3, 7
4, 8 1 2 4 3 5 6 8 7

9. Alternate Interior Angles (also called opposite interiors)
Interior angles on opposite sides of the transversal
4, 6
3, 5 1 2 4 3 5 6 8 7

10. Same-side Interior Angles (also called consecutive interiors)
Interior angles on the same side of the transversal
3, 6
4, 5 1 2 4 3 5 6 8 7

11. Alternate Exterior Angles
Exterior angles on opposite sides of the transversal
1, 7
2, 8 1 2 4 3 5 6 8 7

12. Name the special angle pair for the given angles
Name the special angle pair for the given angles. (One of these has no relationship)
1.) <1 & <5
2.) <10 & <15
3.) <7 & <13
4.) <16 & <8
5.) <11 & <10
6.) <2 & <7
7.) <7 & <14
8.) <9 & <13
9.) <2 & <9
10.) <14 & <6
11.) <16 & <13
12.) <10 & <7
13.) <11 & <15 1 3 5 6 2 4 7 8 9 10 13 14 11 12 15 16