8-4 classifying pairs of lines warm up warm up lesson presentation lesson presentation problem of...
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8-4 Classifying Pairs of Lines
Warm UpWarm Up
Lesson PresentationLesson Presentation
Problem of the DayProblem of the Day
Lesson QuizzesLesson Quizzes
8-4 Classifying Pairs of Lines
Warm UpGive the complement of each angle.
1. 80°
2. 64°
3. 15°
4. 48°
10°
26°
75°
42°
8-4 Classifying Pairs of Lines
Problem of the Day
Draw three points that are not in a straight line. Label them A, B, and C. How many different lines can you draw that contain two of the points? Name the lines.
3; AB, AC, BC
8-4 Classifying Pairs of Lines
Learn to classify pairs of lines.
8-4 Classifying Pairs of Lines
Vocabulary
parallel linesperpendicular linesskew lines
8-4 Classifying Pairs of Lines
Intersecting lines are lines that cross at one common point.
Parallel lines are lines in the same plane that never intersect.
Line YZ intersects line WX.
YZ intersects WX.
Line AB is parallel to line ML.
AB ML.
YW
Z X
B
A
M
L
The red arrows on the lines show that the lines are parallel. Reading Math
8-4 Classifying Pairs of Lines
Perpendicular lines intersect to form 90° angles, or right angles.
Line RS is perpendicular to line TU.
RS TU.S
R
T U
Skew lines are lines that lie in different planes. They are neither parallel nor intersecting.
Line AB and line ML are skew.
AB and ML are skew.
M
L
AB
8-4 Classifying Pairs of Lines
Additional Example 1A: Classifying Pairs of Lines
Classify each pair of lines.
The lines intersect to form right angles.
They are perpendicular.
8-4 Classifying Pairs of Lines
Additional Example 1B: Classifying Pairs of Lines
Classify each pair of lines.
The lines are in different planes and are not parallel or intersecting.
They are skew.
8-4 Classifying Pairs of Lines
Additional Example 1C: Classifying Pairs of Lines
Classify each pair of lines.
The lines are in the same plane. They do not appear to intersect.
They are parallel.
8-4 Classifying Pairs of Lines
Additional Example 1D: Classifying Pairs of Lines
Classify each pair of lines.
The lines cross at one common point.
They are intersecting.
8-4 Classifying Pairs of Lines
Check It Out: Example 1A
Classify each pair of lines.
The lines are in the same plane. They do not appear to intersect.
They are parallel.
8-4 Classifying Pairs of Lines
Check It Out: Example 1B
Classify each pair of lines.
The lines intersect to form right angles.
They are perpendicular.
8-4 Classifying Pairs of Lines
Check It Out: Example 1C
Classify each pair of lines.
The lines are in different planes and are not parallel or intersecting.
They are skew.
8-4 Classifying Pairs of Lines
Check It Out: Example 1D
Classify each pair of lines.
The lines cross at one common point.
They are intersecting.
8-4 Classifying Pairs of Lines
Additional Example 2: Application
The handrails on an escalator are in the same plane. What type of line relationship do they represent?
The handrails are in the same plane and do not intersect.
The lines are parallel.
8-4 Classifying Pairs of Lines
Check It Out: Example 2
The roads are in the same plane. What type of line relationship do they represent?
The lines cross at one common point.
The lines are intersecting.
8-4 Classifying Pairs of Lines
Standard Lesson Quiz
Lesson Quizzes
Lesson Quiz for Student Response Systems
8-4 Classifying Pairs of Lines
Lesson Quiz
1. Sketch a pair of perpendicular lines.
2. Sketch a pair of parallel lines.
Use the figure to classify the lines.
3. AD and BC
4. AD and CF
5. AB and BG
parallel
skew
perpendicular
8-4 Classifying Pairs of Lines
1. Identify a pair of perpendicular lines.
A. B.
C. D.
Lesson Quiz for Student Response Systems
8-4 Classifying Pairs of Lines
2. Identify a pair of skew lines.
A. B.
C. D.
Lesson Quiz for Student Response Systems
8-4 Classifying Pairs of Lines
3. Use the figure to classify the lines
A. parallel
B. perpendicular
C. skew
D. intersecting but not perpendicular
Lesson Quiz for Student Response Systems
8-4 Classifying Pairs of Lines
4. Use the figure to classify the lines
A. parallel
B. perpendicular
C. skew
D. intersecting but not perpendicular
Lesson Quiz for Student Response Systems