Unit 1 NOTES NC Math 2 Honors 1

Day 2: Introduction to Transformations and Translations

Warm-Up:

Introduction to Transformations and Translations

Congruent figures _______________________________________________________________ . When two figures are congruent, you can move one so that ____________________________

_______________________________________________.

Transformation of a geometric figure: change in its ______________, ____________, or ________.

Preimage – ________________ figureNotation: __________

Image – _______ or _______________ figureNotation: __________ ImagePreimage

B'

F'

A'

B

F

A

Isometry – transformation in which preimage and image are the ____________ _____________ and

_______________ (also called: ______________________________________________)

Examples:

___________________ , _____________________ , and __________________ Translation – an isometry that maps all points the ___________ _____________________ and the

___________ ___________________.

Prerequisite Skill: Solving Systems of EquationsSolve for x and y.2. x = 8 + 3y 2x – 5y = 8

3. 5x – y = 20 3x + y = 12

4. x + 3y = 7 x + 2y = 4

5. 19 = 5x + 2y 1 = 3x – 4y

1.

Unit 1 NOTES NC Math 2 Honors 2

Activity 1: Patty Paper TranslationThe translation T is defined by T(A) = B … meaning that it slides the figure the distance AB in the

direction that goes.1) Place the patty paper over this page. Trace the triangle and points A and B.

2) Slide the patty paper along so that the A on the patty paper is on top of B on this sheet

and B on the patty paper is still on on this sheet. 3) The position of the triangle on your patty paper now corresponds to the image of XYZ under

the translation, T. If you press down hard with a sharp pencil, the image of the triangle can be seen on this page when you remove the patty paper.

Translation Vector – an arrow that indicates the distance and direction to translate a figure in a plane. in the activity above is an example of a translation vector.

The notation for a vector is: < -a, b > for a translation a units to the left and b units up.

Three ways to describe a transformation (using example shown right): **Always be specific when completing any type of description!!

1) Words: Translation to the right 10 units and down 4 units.

2) Algebraic rule (motion rule): T: (x, y) -> (x + 10, y – 4)

3) Vector: < 10, - 4 > Activity 2: Dot Paper Translations

1) Use the dots to help you draw the image of the first figure so that A maps to A’.2) Use the dots to help you draw the image of the second figure so that B maps to B’.3) Use the dots to help you draw the image of the third figure so that C maps to C’.4) Complete each of the following translation rules using your mappings from 1 – 3 above.

a) For A, the translation rule is: T:(x, y) ( _______, _______ ) or <_____, _____>b) For B, the translation rule is: T:(x, y) ( _______, _______ ) or <_____, _____>

Z

YX

B

A

B'

A'B

C

Unit 1 NOTES NC Math 2 Honors 3c) For C, the translation rule is: T:(x, y) ( _______, _______ ) or <_____, _____>

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. . . . . . . . . . . . . .Checkpoint: GEO has coordinates G(-2, 5), E(-4, 1) O(0, -2). A translation maps G to G’ (3, 1).

1. Find the coordinates of: a) E’ ( _____, _____) b) O’ ( _____, _____)

2. The translation rule is T: (x, y) ( _______, _______ ) 3. The vector is <_____, _____>

4. Specifically describe the transformation: ________________________________________

Rotations – Discovery Activity

1. Exploration. Triangle A’B’C’ is a rotation of Triangle ABC about the center O. 1) Using a compass, draw the circle that has center O and goes through point A.2) Using a compass, draw the circle that has center O and goes through point B.3) Using a compass, draw the circle that has center O and goes through point C.4) What do you know notice about points A’, B’, and C’? 5) Trace Triangle ABC and point O on patty paper. Put your pencil point on top of the patty paper on

point O and turn the patty paper around and around in both directions (keeping the O on your patty paper on top of the O on this sheet.) What do you notice about the triangle as it rotates around in either direction?

A

A’

B’

B

C’

C

B'

A'B

C

Unit 1 NOTES NC Math 2 Honors 4

2. Bill rotates figure TUV using center V as shown by the arrow. Draw and label the image of figure TUV using appropriate notation. Explain how you made your drawing. Be sure to include the following:

3. Checkpoint and Summary This type of transformation is called a __________________, which is a _____________ in a given direction for a given number of _____________ around a fixed ______________. To rotate an object, you must specify the ________________ of rotation, the _____________ around which the rotation is to occur, and the direction.

Day 3: Rotations with Coordinates and Polygons

Warm-Up: Given triangle ABC with A(-1, 4), B(4, 3) and C(1, -5), graph the image points after the following transformations, identify the coordinates of the image, and write the Algebraic Rule for each.

1) Translate triangle ABC left 3, up 2 Points: Algebraic Rule:

2) Translate triangle ABC right 2, down 1Points: Algebraic Rule:

3) Solve the following system 4m + 18n = 80

the method you used to make your image

what information the arrow tells you

what is point V? What happens to point V after the motion is performed?

U

T

Unit 1 NOTES NC Math 2 Honors 5 12m + 34n = 160

Rotations with a Coordinate Plane and with Polygons

4. Visualizing Rotations Centered About the OriginThe flag shown below is rotated about the origin 90°, 180°, and 270°. Flag ABCDE is the preimage. Flag A’B’C’D’E’ is a 90° counterclockwise rotation of ABCDE.

Notation for Rotations R _________________________ , ___________________________ Example: R O , 90° 5. Rotations on the Coordinate Plane Exploration

1) Triangle ABC has coordinates A(2, 0), B(3, 4), C(6, 4). Trace the triangle and the x- and y-axes on patty paper.

NOTE: Unless otherwise specified, the standard for rotations is counterclockwise!

______________

_____________ Degrees!

________ - __________

___________ Degrees!

Unit 1 NOTES NC Math 2 Honors 62) Rotate Triangle ABC 90, using the axes you traced to help you line it back up. Record the

new coordinates. A’( _____ , _____ ), B’( _____ , _____ ), C’( _____ , _____ )

3) Rotate Triangle ABC 270, using the axes you traced to help you line it up. Record the new coordinates. A’( _____ , _____ ), B’( _____ , _____ ), C’( _____ , _____ )

4) Rotate Triangle ABC 180, using the axes you traced to help you line it back up correctly.

Record the new coordinates. A’( _____ , _____ ), B’( _____ , _____ ), C’( _____ , _____ )

Checkpoint: Look at the patterns and complete the rule. Then write the rule using proper notation for 1 – 3.

1. A 90 counter-clockwise rotation maps (x, y) ( _______, _______ ). Notation: __________

2. A 270 counter-clockwise rotation maps (x, y) ( _______, _______ ). Notation: __________

3. A 180 rotation maps (x, y) ( _______, _______ ). Notation: __________

4. A rotation of 270 clockwise is equivalent to a rotation of ______________________________.

5. A rotation of 270° counterclockwise is equivalent to a rotation of _________________________.

6. Rotations with Polygons

Part 1 – Regular Polygons and rotation symmetryA few definitions to support you as you work: A regular polygon is a polygon that is equiangular (all angles are equal in measure) and equilateral (all sides have the same length). In the case of regular polygons the center is the point that is equidistant from each vertex.

1. Given regular triangle EFG with center O.a. F is rotated about O. If the image of F is G, what is the angle of rotation?

b. is rotated 120° about O. What is the image of ?

General Rule: The regular triangle has rotation symmetry with respect to the center of the polygon

and angles of rotation that measure _____ and _____.

Side note: A regular triangle is also called an ______________ triangle or an _______________ triangle.

2. Given regular quadrilateral EFGH with center O.a. F is rotated about O. If the image of F is G, what is the angle of rotation?

b. F is rotated about O. If the image of F is H, what is the angle of rotation?

Unit 1 NOTES NC Math 2 Honors 7

c. is rotated 270° about O. What is the image of ?

General Rule: The regular quadrilateral has rotation symmetry with respect to the center of the polygon

and angles of rotation that measure _____, _____,______ and _____.

Side note: A regular quadrilateral is often called a _______________.

3. Given regular pentagon ABCDE with center O,

a. C is rotated about O. If the image of C is D, what is the angle of rotation?

b. C is rotated about O. If the image of C is E, what is the angle of rotation?

c. C is rotated about O. If the image of C is A, what is the angle of rotation?

d. is rotated 288° about O, what is the image of ?

e. Pentagon ABCDE is rotated 72° about O, what is the image of pentagon ABCDE (in terms of the original points’ labels – do not use A’B’C’D’E’)?

f. Explain the significance of the multiples of 72°.

General Rule: The regular pentagon has rotation symmetry with respect to the center of the polygon

and angles of rotation that measure _____, _____,_____, ______ and _____.

4. Given regular hexagon ABCDEF with center O,

a. C is rotated 60° about O, what is the image of C?

b. C is rotated 120° about O, what is the image of C?

c. C is rotated 180° about O, what is the image of C?

d. is rotated 240° about O, what is the image of ?

e. Explain the significance of the multiples of 60°.

General Rule: The regular hexagon has rotation symmetry with respect to the center of the polygon

and angles of rotation that measure _____, _____, _____, _____, ______ and _____.

Unit 1 NOTES NC Math 2 Honors 85. Given regular octagon ABCDEFGH with center O,

a. When point C is rotated about O, the image of point C is point D. Describe the rotation (be sure to include degree).

b. When point C is rotated about O, the image of point C is point F. Describe the rotation (be sure to include degree).

A regular polygon can be mapped onto itself if we rotate in multiples of the central angle measure.

The central angle of a regular polygon is found by ______________________________

Part 2 – Parallelograms and rotation symmetry

6. Given parallelogram ABCD, there is a center of rotation, O, that will map point A onto point C.

a. What are the coordinates of O?

b. What degree of rotation mapped C onto A using the center O?

c. If we rotate the parallelogram around center O using the degree measure found in part b, angle D maps to angle _________.

d. If angle A maps to angle C, then angle A and angle C are _________.

e. If angle D maps to angle ____, then angle D and angle _____ are _________.