Chapter 4.1 Skew, Parallel and Perpendicular Lines.

Post on 18-Dec-2015

257 views 5 download

Transcript of Chapter 4.1 Skew, Parallel and Perpendicular Lines.

Chapter 4.1Skew, 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 LINESFA and BD are SKEW LINES

G BAF

E

HD

C

A B

D C

E F

H G

Use the figure to find the following:Use the figure to find the following:

Two pairs ofParallel Lines

Two pairs ofParallel Planes

Two pairs of Skew Lines

GC HD

AB CD Plane AED Plane BCF AD, BF

EH, CGPlane EFG Plane ABC

PARALLEL LINES

• Def: lines that do not intersect; must be coplanar.

• Illustration:

• Notation: l || m AB || CD

lm

A

B

C

D

p. 129

28

A B

C D

Two lines are parallel if they do not intersect.

CDAB

Read as line AB is parallel to line CD.

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

PERPENDICULAR LINES

• Def: Lines that intersect to form a right angle.

• Illustration:

• Notation: m n

• Key Fact: 4 right angles are formed.

m

n

p. 79

29

PERPENDICULAR• Lines that intersect to form

right angles.

90° 90°

90°90°

When two lines intersect at right angles,

They are called perpendicular lines.┴

TRICK: 4 right angles are formed, but it shows 1 only. (The other 3 are invisible.)

Ex. of Perpendicular Lines• Window panes• Streets: Belmont and Cicero

Language of Geometry

Parallel lines & Transversal

Angles, Parallel Lines & Transversal

Homework

p. 144,

1-9,

15-17