Skew, Parallel and Perpendicular Lines

1
Chapter 4.1

• Skew, Parallel and Perpendicular Lines

2
Objectives Well learn

• Define the characteristics of skew, parallel and
  perpendicular lines.

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Skew Lines

• Skew lines lie in different planes. They are
• Not parallel
• Not intersecting
• Not perpendicular.

4
Skew lines

• Skew lines are noncoplanar lines.
• (Noncoplanar lines cannot intersect.)

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SKEW LINES

• Lines that lie in different planes. They are
  neither parallel nor intersecting.

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SKEW LINES

• Lines that lie in different planes. They are
  neither parallel nor intersecting.

CD and FA are SKEW LINES FA and BD are SKEW
LINES
G
B
A
F
H
D
E
C
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Use the figure to find the following
A
B
E
F
D
C
H
G
Two pairs of Parallel Lines
Two pairs of Parallel Planes
Two pairs of Skew Lines
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PARALLEL LINES
28

• Def lines that do not intersect must be
  coplanar.
• Illustration
• Notation l m AB CD

p. 129
9
Two lines are parallel if they do not intersect.
EX1 Are the lines parallel?
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Examples of Parallel Lines

• Hardwood Floor
• Opposite sides of windows, desks, etc.
• Parking slots in parking lot
• Parallel Parking
• Streets Laramie LeClaire

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Examples of Parallel Lines

• Streets Belmont School

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PERPENDICULAR LINES
29

• Def Lines that intersect to form a right angle.
• Illustration
• Notation m ? n
• Key Fact 4 right angles are formed.

p. 79
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PERPENDICULAR

• Lines that intersect to form right angles.

90
90
90
90
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When two lines intersect at right angles,
TRICK 4 right angles are formed, but it shows 1
only. (The other 3 are invisible.)
-

• They are called perpendicular lines.

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Ex. of Perpendicular Lines

• Window panes
• Streets Belmont and Cicero

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Language of Geometry
17
Parallel lines Transversal
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Angles, Parallel Lines Transversal
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Homework
p. 144, 1-9, 15-17