Do Now (4, –6) (12, 27) (–6, 2) Course 2 8-10 Translations, Reflections, and Rotations 1. Subtract 3 from the x-coordinate and 2 from the y-coordinate.

Do Now

(4, –6)(12, 27)

(–6, 2)

Course 2

8-10 Translations, Reflections, and Rotations

1. Subtract 3 from the x-coordinate and 2 from the y-coordinate in (7, –4).

2. Multiply each coordinate by 3 in (4, 9).

3. Subtract 4 from the x-coordinate and add 3 to the to the y-coordinate in (–2, –1).

Hwk: p 77 #1-4

GEORGIA PERFORMANCE STANDARDS:M7G2.a Demonstrate understanding of translations, dilations, rotations, reflections, and relate symmetry toappropriate transformations; M7G2.b Given a figure in the coordinate plane, determine the coordinates resultingfrom a translation, dilation, rotation, or reflection

EQ: How do I recognize, describe, and show transformations?

Vocabulary

transformationimagetranslationreflectionline of reflectionrotation

Insert Lesson Title Here

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VocabularyTransformation- changes the position or orientation of a figureImage- resulting figure Translation- slides without turning Reflection- flips across a line of reflection line of reflection- x or y axis Rotation- turns around a fixed pointDilation- make bigger or smaller


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In mathematics, a transformationchanges the position or orientation of a figure. The resulting figure is the imageof the original. Images resulting fromthe transformations described in the next slides are congruent to the original figures.

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TranslationThe figure slides along a straight line without turning.

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Types of Transformations

ReflectionThe figure flips across a line of reflection, creating a mirror image.

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RotationThe figure turns around a fixed point.

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Identify each type of transformation.

Additional Example 1: Identifying Types of Transformations

The figure flips across the y-axis.

A. B.

It is a translation.Course 2


It is a reflection.

The figure slides along a straight line.


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The point that a figure rotates around may be on the figure or away from the figure.

Helpful Hint

Check It Out: Example 1

Identify each type of transformation.

A. B.


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x

y

2

2

–2

–4

4

4

–4

–2 0

x

y

2

2

–2

–4

4

4

–4

–2 0

It is a translation.

The figure slides along a straight line.

It is a rotation.

The figure turns around a fixed point.

Additional Example 2: Graphing Transformations on a Coordinate Plane

Graph the translation of quadrilateral ABCD 4 units left and 2 units down.

Each vertex is moved 4 units left and 2 units down.

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A’ is read “A prime” and is used to represent the point on the image that corresponds to point A of the original figure

Reading Math

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Translate quadrilateral ABCD 5 units left and 3 units down.

Each vertex is moved five units left and three units down.

x

yA

B

C

2

2

–2

–4

4

4

–4

–2 D

D’C’

B’A’

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Graph the reflection of the figure across the indicated axis. Write the coordinates of the vertices of the image.

x-axis, then y-axis

Additional Example 3: Graphing Reflections on a Coordinate Plane

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A. x-axis.

Additional Example 3 Continued

The x-coordinates of the corresponding vertices are the same, and the y-coordinates of the corresponding vertices are opposites.

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The coordinates of the vertices of triangle ADC are A’(–3, –1), D’(0, 0), C’(2, –2).

B. y-axis.

Additional Example 3 Continued

The y-coordinates of the corresponding vertices are the same, and the x-coordinates of the corresponding vertices are opposites.

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The coordinates of the vertices of triangle ADC are A’(3, 1), D’(0, 0), C’(–2, 2).

Check It Out: Example 3A


3

x

y

A

B

C

3

–3

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Graph the reflection of the triangle ABC across the x-axis. Write the coordinates of the vertices of the image.

The x-coordinates of the corresponding vertices are the same, and the y-coordinates of the corresponding vertices are opposites.

The coordinates of the vertices of triangle ABC are A’(1, 0), B’(3, –3), C’(5, 0).

A’

B’

C’

Check It Out: Example 3B


A x

y

B

C

3

3

–3

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Graph the reflection of the triangle ABC across the y-axis. Write the coordinates of the vertices of the image.

The y-coordinates of the corresponding vertices are the same, and the x-coordinates of the corresponding vertices are opposites.

The coordinates of the vertices of triangle ABC are A’(0, 0), B’(–2, 3), C’(–2, –3).C’

B’

Triangle ABC has vertices A(1, 0), B(3, 3), C(5, 0). Rotate ∆ABC 180° about the vertex A.

Additional Example 4: Graphing Rotations on a Coordinate Plane

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x

y

A

B

C

3

–3

The corresponding sides, AC and AC’ make a 180° angle.

Notice that vertex C is 4 units to the right of vertex A, and vertex C’ is 4 units to the left of vertex A.

C’

B’

A’

Triangle ABC has vertices A(0, –2), B(0, 3), C(0, –3). Rotate ∆ABC 180° about the vertex A.


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The corresponding sides, AB and AB’ make a 180° angle.

Notice that vertex B is 2 units to the right and 3 units above vertex A, and vertex B’ is 2 units to the left and 3 units below vertex A.

x

y

B

C

3

3

–3B’

C’

A

TOTD

1. Identify the transformation.

(1, –4), (5, –4), (9, 4)

reflection


2. The figure formed by (–5, –6), (–1, –6), and (3, 2) is transformed 6 units right and 2 units up. What are the coordinates of the new figure?

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TOTD

3. Graph the triangle with vertices A(–1, 0), B(–3, 0), C(–1, 4). Rotate ∆ABC 90° counterclockwise around vertex B and reflect the resulting image across the y-axis.


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x

y

2

–2

2–2–4

–4

4

4

C

B AC’

B’

A’

C’’A’’

B’’

Do Now (4, –6) (12, 27) (–6, 2) Course 2 8-10 Translations, Reflections, and Rotations 1. Subtract 3 from the x-coordinate and 2 from the y-coordinate.

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