thursday, january 26th

Thursday, January 26th• Please complete the warm up and write

down homework

Warm Up1. How do you know if two shapes are

similar?

2. Sharon bought a shirt for $42.50 and a pair of jeans for $52.75. If there’s a 8% sales tax. What will the total be?

Corny Joke of the Day

What type of animal needs oil?

Mice because they

“squeak”

Have you used your holiday present yet?

Staple your extra 10 points to any Homework, Quiz, or

Classwork assignment Turn it into the math bin

Checkpoint Answers Scored out of 14

GREAT JOB!!!! Remember to watch your decimal

placements

Symmetry Preview

Write down your definition of

symmetry and draw examples that you think represent it!

Symmetry

OUR MISSION

Learn to identify line symmetry and learn how to rotate figures!

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.

What is it?

Part 1 Lines of symmetry in regular polygons

Regular polygons: All side lengths and angles are

congruent

Can you find the rule?Find the number of lines of

symmetry in each shape and fill out the chart.Shape Number of Sides Lines of symmetry

Triangle

Square

Pentagon

Hexagon

Octagon

4 lines of symmetry

DiscoveryFor a regular

polygon the lines of symmetry is the same as

the number of sides!

Fun FactA dodecagon is a 12-

sided regular polygon. This means that it has

___________lines of symmetry!

Part 2 Determining if the lines given are the lines

of symmetry

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

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.

#1

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

The two parts of the figure do not appear congruent.

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

#2

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

The two parts of the figure do not appear congruent.

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

#3

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

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.

#4

Group DiscussionHow many lines of symmetry does the following shape have?

NOT EVERY SHAPE HAS A

LINE OF SYMMETRY

Does this have a line of symmetry?

1 line of symmetry

Is there a line of symmetry. If so, how many?

Smile Symmetry

Corporate Logos Find the symmetry

Class Discussion 1. Situations that demonstrate

reflection

2. Situations that demonstrate rotation?

Transformations

Cut out the first letter to your name!

A rigid transformation moves a figure without changing its size or shape. So the original figure and the transformed figure are always congruent.

The illustrations of the alien will show three transformations: • A rotation• A reflection• A translation*Notice the transformed alien does not change in size or shape.

Type #1 Rotational

A rotation is the movement of a figure around a point. A point of rotation can be on or outside a

figure.

The location and position of a figure can change with a rotation.

The figure moves around a point.

It is a rotation.

Example #1

The figure moves around a point.

It is a rotation.

Example #2

Rotations are measured by Degrees.

Rotations can turn Clockwise or Counter Clockwise

Clockwise“like a clock”

Counter-Clockwise“opposite of a

clock”

90°

180°

360°

• A full turn is 360°• of a turn is ¼ 90°• of a turn is ½180°• of a turn is ¾270°

Just Watch! Draw a 180° rotation about the point

shown.

Trace the figure and the point of rotation.Place your pencil on the point of rotation.Rotate the figure 180°.Trace the figure in its new location.

Draw each transformation.Draw a 180° clockwise rotation about the point shown.

Trace the figure and the point of rotation.Place your pencil on the point of rotation.Rotate the figure 180°.Trace the figure in its new location.

A AYou Try #1!

Draw each transformation.Draw a 90° counter clockwise rotation about the point shown.

Trace the figure and the point of rotation.Place your pencil on the point of rotation.Rotate the figure 90° Trace the figure in its new location.

K

You Try #2! K

Type #2 Reflection

When a figure flips over a line, creating a mirror image, it is called a reflection. The line the figure is flipped over is called line of reflection.

The location and position of a figure change with a reflection.

There are 2 types!

Horizontal: flips ACROSS

Vertical: flips UP and DOWN

Practice Problems1. Reflect Vertically

2. Reflect horizontally

J

B

TYPE #3 TRANSLATION

A translation is the movement of a figure along a straight line.

Only the location of the figure changes with a translation.

WHITEBOARD PRACTICE

Determine the transformation!

The figure is flipped over a line.

It is a reflection.

The figure is moved along a line.

It is a translation.

The figure moves around a point.

It is a rotation.

The figure is flipped over a line.

It is a reflection.

The figure moves around a point.

It is a rotation.

The figure is moved along a line.

It is a translation.