1. 3-1 Lines and Angles Warm Up Lesson Presentation Lesson Quiz
Holt Geometry
Warm Up
Lesson Presentation
Lesson Quiz

2. 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
coplanar points
supplementary angles
point
linear pair

3. Objectives Identify parallel, perpendicular, and skew lines.
Identify the angles formed by two lines and a transversal.

4. Parallel Lines Def: lines that do not intersect. Illustration:
Notation: l || m AB || CD A B C D l m

5. Examples of Parallel Lines
Hardwood Floor
Opposite sides of windows, desks, etc.
Parking slots in parking lot
Streets: Franklin Ave & Bloomfield Ave

6. Perpendicular Lines Def: Lines that intersect to form a right angle.
Illustration:
Notation: m  n
Key Fact: 4 right angles are formed. m n

7. Example of Perpendicular Lines
Streets: Franklin Ave and Center Street

8. Skew Lines
Def: (NOT coplanar) Skew lines are NOT parallel lines and do not intersect
Illustration:
Notation: AE and CD are skew.

10. Skew lines continued Are the following lines skew…? Yes, they are skew
1. AE and FB?
No, they are ||
2. FB and CG?
No, they are || -- even though we
can’t see it, a plane COULD connect them
3. AE and BD?
Yes, they are skew

11. are planes that do not intersect.
Parallel Planes
are planes that do not intersect.
Plane AEB || plane CGH

12. Segments or rays are parallel, perpendicular, or skew if the lines that contain them are parallel, perpendicular, or skew.
Helpful Hint

13. Check It Out! Example 1
Identify each of the following.
a. a pair of parallel segments
BF || EJ
b. a pair of skew segments
BF and DE are skew.
c. a pair of perpendicular segments
BF  FJ
d. a pair of parallel planes
plane FJH || plane BCD

14. Example 1: Identifying Types of Lines and Planes
Identify each of the following.
E. a pair of parallel segments
LM ||QR
F. a pair of skew segments
KN and PQ
G. a pair of perpendicular segments
NS  SP
H. a pair of parallel planes
plane NMR || plane KLQ

15. Lesson Quiz: Part I
Identify each of the following.
I. a pair of parallel segments
EH || FG
J. a pair of skew segments
BF and EH
K. a pair of perpendicular segments
CG  GH
L. a pair of parallel planes
ABC and EFG

16. Parallel
neither
perpedicular

17. No, they intersect
Yes, they are skew.

18. Plane C
Plane D

19. 1. Line x and line y
2. Line x and line z
3. Line y and line z

20. 4. QU TX ST RQ
5. Plane RST
6. WS WX UV RV