&&66 **Measure, 'UDZSRLQWVOLQHVOLQHVHJPHQWVUD\VDQJOHVULJKWDFXWH MG 2.1 identify, and draw angles, perpendicular and parallel REWXVH DQGSHUSHQGLFXODUDQGSDUDOOHOOLQHV,GHQWLI\WKHVHLQWZRGLPHQVLRQDOILJXUHV

UNDERLYING SKILLS AND CONCEPTS:

lines, rectangles, and triangles, by using appropriate tools (e.g., straightedge, ruler, compass, protractor, drawing software).

lines; parallel lines; perpendicular lines

Understand Parallel and Perpendicular Parallel lines lie on a flat surface or plane. They never intersect even if they are extended. Line l is parallel to line m. Intersecting lines meet at one point. MT at point P. Line !"# ST intersects line !"#

S M

Perpendicular lines form right angles when they intersect. Line k is perpendicular to line g.

l m

N P T

You can name a line using two points on the line.

k

Or, you can name a line with one letter.

g

E x am p l E

Use a compass and a straightedge to draw perpendicular lines. C !D ! is called the perpendicular bisector of the line segment A !B !. C

C M

A

B

A

A

B

B D

E x am p l E

A

B D

2

Use a compass and a straightedge to draw parallel lines. You can use what you know about perpendicular lines to construct parallel lines. C

C

Line segment C !D ! is perpendicular to line segment ! A! B.

s A

M D

page 292

B

A

M D

B

Line s is perpendicular to line segment C !D ! and parallel to line segment ! A! B.

Chapter 25 – Lesson 2

E – © CSL Associates, Inc. All rights reserved.

1

Name

P RAC T I C E Use the diagram. 1. Name a pair of perpendicular lines.

X

BD Possible answer: Lines  AC and 

E

B

2. Name a pair of parallel lines.

Possible answer: Lines  BE and  AC .

A

C D

Y

Use a compass and a straightedge. Check student’s drawings. 3. Draw point line l. Construct line t

perpendicular to l. Possible answer:

4. Draw a line m and put points R and S

on m. Construct one line through R and another line through S that they are parallel to each other.

E – © CSL Associates, Inc. All rights reserved.

Possible answer:

Choose the best answer. Explain. 5. Which lines will never intersect?

CD A  AB and   B  AC and  CD 

A E C D

BD C  AC and  

F

 BD appear to be parallel. AC and 

D  BE and  CF 

Math Reasoning

B

Lines

MR 1.1

6. Look at the diagram at the top of the page. How many right angles are formed when a

line is perpendicular to two parallel lines? 8 right angles 7. How many right angles are formed when a perpendicular line intersects three parallel lines?

12 right angles

Chapter 25 – Lesson 2

page 293

MCX94.HW.CL.G5.FM&Lesson.v211

8/2/04

18:03

Page 196

Name

…at home!

P RAC T I C E Use the diagram. 1. Name a pair of parallel lines.

X

Lines XY and EC

E

B

2. Name a pair of perpendicular lines.

A

C

Lines BD and AC D

Y

Use a compass and a straightedge. Check drawings. 3. Draw point line l. Construct line g

perpendicular to l.

4. Draw a line m and put points A and B

on m. Construct one line through A and another line through B that they are parallel to each other.

Possible answer:

Choose all the best answers. Explain. 5. Which lines will intersect? A  AB and  CD   CD B  AC and   

A C

C  AC and  BD

D

D  BE and  CF  

Math Reasoning

B

E

F

 BD appear to be parallel, AC and  all the other lines intersect.

Lines

MR 1.1

6. Look at the diagram at the top of the page. How many right angles are

formed when a line is perpendicular to two parallel lines? 8 right angles 7. How many right angles are formed when a perpendicular line intersects

four parallel lines? 16 right angles page 196

Home Resource and Homework

Chapter 25 Lesson 2

E – © CSL Associates, Inc. All rights reserved.

Possible answer:

MCX94TEG5CH01_32.v7.4.2 2/24/01 19:49 Page 539

Name

P RAC T I C E Use the diagram. 1. Name a pair of perpendicular lines.

X

BD Possible answer: Lines  AC and 

E

B

2. Name a pair of parallel lines.

A

Possible answer: Lines  BE and  AC .

C D

Y

Use a compass and a straightedge. Check student’s drawings. 3. Draw point line l. Construct line t

perpendicular to l.

4. Draw a line m and put points R and S

on m. Construct one line through R and another line through S that they are parallel to each other.

Possible answer: t

Possible answer: m

l S

E – © CSL Associates, Inc. All rights reserved.

R

Choose the best answer. Explain. 5. Which lines will never intersect? A  AB and  CD  B  AC and  CD 

A E C D

C  AC and  BD 

F

 BD appear to be parallel. AC and 

CF D  BE and  

Math Reasoning

B

Lines

MR 1.1

6. Look at the diagram at the top of the page. How many right angles are formed when a

line is perpendicular to two parallel lines? 8 right angles 7. How many right angles are formed when a perpendicular line intersects three parallel lines?

12 right angles

Chapter 25 – Lesson 2

Student Book Page

page 293

Name

…at home!

P RAC T I C E Use the diagram. 1. Name a pair of parallel lines.

X

Lines XY and EC

E

B

2. Name a pair of perpendicular lines.

A

C

Lines BD and AC D

Y

Use a compass and a straightedge. Check drawings. 3. Draw point line l. Construct line g

perpendicular to l.

4. Draw a line m and put points A and B

on m. Construct one line through A and another line through B that they are parallel to each other.

Possible answer: g

Possible answer: m B

A

Choose all the best answers. Explain. 5. Which lines will intersect?

CD A  AB and    CD B  AC and   

A C

C  AC and  BD

D

D  BE and  CF  

Math Reasoning

B

E

F

 AC and  BD appear to be parallel, all the other lines intersect.

Lines

MR 1.1

6. Look at the diagram at the top of the page. How many right angles are

formed when a line is perpendicular to two parallel lines? 8 right angles 7. How many right angles are formed when a perpendicular line intersects

four parallel lines? 16 right angles page 196

Home Resource and Homework

Chapter 25 Lesson 2

E – © CSL Associates, Inc. All rights reserved.

l