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Chapter 4.1. Skew, Parallel and Perpendicular Lines. Objectives: We’ll learn…. Define the characteristics of skew, parallel and perpendicular lines. Skew Lines. Skew lines lie in different planes . They are Not parallel Not intersecting Not perpendicular. Skew lines.
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Chapter 4.1 Skew, Parallel and Perpendicular Lines
Objectives: We’ll learn… • Define the characteristics of skew, parallel and perpendicular lines.
Skew Lines • Skew lines lie in different planes. They are • Not parallel • Not intersecting • Not perpendicular.
Skew lines Skew lines are noncoplanar lines. (Noncoplanar lines cannot intersect.)
SKEW LINES • Lines that lie in different planes. They are neither parallel nor intersecting.
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 F A H D E C
Use the figure to find the following: A B E F D C H G Two pairs of Parallel Planes Two pairs of Parallel Lines Two pairs of Skew Lines
B A D l C m 28 PARALLEL LINES • Def: lines that do not intersect; must be coplanar. • Illustration: • Notation:l || mAB|| CD p. 129
A B C D Read as line AB is parallel to line CD. Two lines are parallel if they do not intersect. EX1: Are the lines parallel?
Examples of Parallel Lines • Hardwood Floor • Opposite sides of windows, desks, etc. • Parking slots in parking lot • Parallel Parking • Streets: Laramie & LeClaire
Examples of Parallel Lines • Streets: Belmont & School
m n 29 PERPENDICULAR LINES • Def: Lines that intersect to form a right angle. • Illustration: • Notation:m n • Key Fact: 4 right angles are formed. p. 79
PERPENDICULAR • Lines that intersect to form right angles. 90° 90° 90° 90°
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. ┴
Ex. of Perpendicular Lines • Window panes • Streets: Belmont and Cicero
Homework p. 144, 1-9, 15-17