1. 3.1 Parallel lines and transversals
Warm Up
Identify each of the following.
1. points that lie in the same plane
2. two angles whose sum is 180°
3. the intersection of two distinct intersecting lines
4. a pair of adjacent angles whose non-common sides are opposite rays

2. Parallel lines are two lines in a plane that never intersect.
Symbol: EF // GH .
Skewed lines are lines in different planes that are not parallel but will never intersect.

3. A. Name all planes that are parallel to plane WPZ.
B. Name all segments that intersect line XQ.
C. Name all segments that are parallel to line SR.
D. Name all segments that are skew to line PS.

4. Identify each of the following.
a. a pair of parallel segments
b. a pair of skew segments
c. a pair of perpendicular segments
d. a pair of parallel planes

5. Line n is called the transversal of the two parallel lines.
A transversal is a line that intersects two or more lines.
When a transversal intersects two lines, 8 angles are formed.

7. Exterior Angles: Outside // lines.
Interior Angles: Inside // lines.
Same-Side (Consecutive) Interior Angles: Both inside and on the same side of transversal.
Same-Side (Consecutive) Exterior Angles: Both outside and same side of transversal.

8. Alternate Exterior Angles: Both outside and opposite sides of transversal.
Alternate Interior angles: (form a Z), both inside and opposite sides of the transversal.
Corresponding angles: (form a F) One in and one out but on the same side of transversal.

9. Give an example of each angle pair.
A. corresponding angles
B. alternate interior angles
C. alternate exterior angles
D. same-side interior angles

10. Lines do not have to be parallel to following special names; they just do not have any special relationships.
Give the special name for:
∠1, ∠ 7
∠ 2, ∠ 8
∠ 4, ∠ 6
∠ 1, ∠ 5
∠ 6, ∠ 2
∠ 6, ∠ 8
∠ 5, ∠ 8

11. If the lines are parallel, then the 8 angles form special relationships.
4 angles are acute: a, d, e, h are congruent.
4 angles are obtuse: b, c, f, g are congruent.
The sum of an acute and obtuse angles equals 180 degrees.

12. Line a // line b
Angle
Special Name
Relationship
∠ 1, ∠ 5
∠ 7, ∠6
∠8, ∠ 4
∠ 3, ∠ 6
∠ 4, ∠ 6
∠ 1, ∠ 8
∠ 2, ∠ 8

13. Give the special name for:
A) ∠1, ∠8 E) ∠4, ∠1
B) ∠12, ∠14 F) ∠6, ∠8
C) ∠9, ∠16 G) ∠1, ∠5
D) ∠13, ∠16 H) 11, ∠13

14. Identify the transversal and classify each angle pair.
A. 1 and 3
B. 2 and 6
C. 4 and 6

15. Lesson Quiz:
Identify each of the following.
1. a pair of parallel segments
2. a pair of skew segments
3. a pair of perpendicular segments
4. a pair of parallel planes