6th Grade Math HomeworkChapter 7.10

Page 367-368

#6-14 & SR

ANSWERS

6th Grade Math HomeworkChapter 7.11

Page 371-372

#1-8

& Spiral Review

Ch 7 Learning Goal: PLANE GEOMETRY• Learn to describe the figures by using the terms of geometry (7-1)• Learn to name, measure, classify, estimate and draw angles (7-2)• Learn to understand relationship of angles (7-3)• Learn to classify the different types of lines (7-4)• Learn to classify triangles and solve problems involving angle and side

measures of triangles (7-5)• Learn to identify, classify, and compare quadrilaterals (7-6)• Learn to identify regular and not regular polygons and to find the angle

measures of regular polygons (7-7)• Learn to recognize, describe, and extend geometric patterns (7-8)• Learn to identify congruent figures and to use congruence to solve

problems (7-9)• Learn to use translations, reflections, and rotations to transform geometric

shapes (7-10)• Learn to identify line symmetry (7-11)• Learn to identify tessellations and shapes that can tessellate (7-12)

7-11 Symmetry

Course 1

Warm UpWarm Up

Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

Warm UpTrue or false?

1. In a reflection the original figure is flipped over a line of symmetry.

2. In a translation the original figure slides along a straight line and is flipped.

3. In a rotation a figure is moved around a point.

true

false

true

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7-11 Symmetry

Problem of the Day

Name four plane figures that can be rotated 180° around a center point and look the same after the rotation as they did before.

Possible answer: rectangle, square, parallelogram, regular hexagon

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7-11 Symmetry

Today’s Learning Goal Assignment

Learn to identify line symmetry.

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7-11 Symmetry

Vocabulary

line symmetryline of symmetry

Insert Lesson Title Here

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7-11 Symmetry

A figure has line symmetry if it can be folded or reflected so that the two parts of the figure match, or are congruent. The line of reflection is called the line of symmetry.

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7-11 Symmetry

Additional Example 1A: Identifying Lines of Symmetry

Determine whether each dashed line appears to be a line of symmetry.

A.The two parts of the figure appear to match exactly when folded or reflected across the line.

The line appears to be a line of symmetry.

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7-11 Symmetry

Additional Example 1B: Identifying Lines of Symmetry

Determine whether each dashed line appears to be a line of symmetry.

B.The two parts of the figure do not appear congruent.

The line does not appear to be a line of symmetry.

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7-11 Symmetry

Try This: Example 1A

Determine whether each dashed line appears to be a line of symmetry.

A.

The two parts of the figure do not appear congruent.

The line does not appear to be a line of symmetry.

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7-11 Symmetry

Try This: Example 1B

Determine whether each dashed line appears to be a line of symmetry.

B.The two parts of the figure appear to match exactly when folded or reflected across the line.

The line appears to be a line of symmetry.

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7-11 Symmetry

Some figures have more than one line of symmetry.

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7-11 Symmetry

Additional Example 2A: Finding Multiple Lines of Symmetry

Find all of the lines of symmetry in the regular polygon.

A. Trace the figure and cut it out.

Fold the figure in half in different ways.

Count the lines of symmetry.

5 lines of symmetry

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7-11 Symmetry

Additional Example 2B: Finding Multiple Lines of Symmetry

Find all of the lines of symmetry in the regular polygon.

B.

Count the lines of symmetry.

8 lines of symmetry

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7-11 Symmetry

Additional Example 2C: Finding Multiple Lines of Symmetry

Find all of the lines of symmetry in the regular polygon.

C.

Count the lines of symmetry.

4 lines of symmetry

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7-11 Symmetry

Try This: Example 2A

Find all of the lines of symmetry in the regular polygon.

A.

1 line of symmetry

Count the lines of symmetry.

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7-11 Symmetry

Try This: Example 2B

Find all of the lines of symmetry in the regular polygon.

B.

Count the lines of symmetry.

4 lines of symmetry

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7-11 Symmetry

Try This: Example 2C

Find all of the lines of symmetry in the regular polygon.

C.Count the lines of symmetry.

4 lines of symmetry

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7-11 Symmetry

Additional Example 3A: Social Studies Application

Find all of the lines of symmetry in the flag.

A. Alaska

There are no lines of symmetry.

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7-11 Symmetry

Additional Example 3B: Social Studies Application

Find all of the lines of symmetry in the flag.

B. Arizona

1 line of symmetryCourse 1

7-11 Symmetry

Additional Example 3C: Social Studies Application

Find all of the lines of symmetry in the flag.

C. Colorado

1 line of symmetryCourse 1

7-11 Symmetry

Additional Example 3D: Social Studies Application

Find all of the lines of symmetry in the flag.

D. New Mexico

2 lines of symmetryCourse 1

7-11 Symmetry

Try This: Example 3A

2 lines of symmetry

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Find all of the lines of symmetry in each design.

There are no lines of symmetry.Course 1

7-11 Symmetry

Try This: Example 3B

Find all of the lines of symmetry in each design.

1 line of symmetryCourse 1

7-11 Symmetry

Try This: Example 3C

Find all of the lines of symmetry in each design.

2 lines of symmetry

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Try This: Example 3D

Find all of the lines of symmetry in each design.

Lesson Quiz

Does the described figure have line symmetry?

1. right isosceles triangle

2. rectangle

Do the following capital letters of the alphabet

have symmetry? If so, is the line of symmetry

horizontal or vertical?

3. H 4. R

yes

yes

Insert Lesson Title Here

yes, vertical and horizontal no

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7-11 Symmetry