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# 5-6 - PowerPoint PPT Presentation

5-6. Congruence. Warm Up. Problem of the Day. Lesson Presentation. Pre-Algebra. Learning Goal Assignment Learn to use properties of congruent figures to solve problems. Vocabulary. correspondence. A correspondence is a way of matching up two sets of objects.

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5-6

Congruence

Warm Up

Problem of the Day

Lesson Presentation

Pre-Algebra

Learning Goal Assignment

Learn to use properties of congruent figures to solve problems.

Vocabulary

correspondence

If two polygons are congruent, all of their corresponding sides and angles are congruent. In a congruence statement, the vertices in the second polygon are written in order of correspondence with the first polygon.

Additional Example 1A: Writing Congruent Statements

Write a congruence statement for the pair of polygons.

The first triangle can be named triangle ABC. To complete the congruence statement, the vertices in the second triangle have to be written in order of the correspondence.

A@Q, so A corresponds to Q.

B@R, so B corresponds to R.

C@P, so C corresponds to P.

The congruence statement is triangle ABC@ triangle QRP.

Try This: Example 1A

Write a congruence statement for the pair of polygons.

The first trapezoid can be named trapezoid ABCD. To complete the congruence statement, the vertices in the second trapezoid have to be written in order of the correspondence.

A

B

|

60°

60°

||

||||

120°

120°

|||

D

C

A@S, so A corresponds to S.

Q

R

|||

120°

120°

B@T, so B corresponds to T.

||

||||

C@Q, so C corresponds to Q.

60°

60°

|

D@R, so D corresponds to R.

T

S

The congruence statement is trapezoid ABCD@ trapezoid STQR.

Pre-Algebra HW

Page 741

#1-10

Additional Example 1B: Writing Congruent Statements

Write a congruence statement for the pair of polygons.

The vertices in the first pentagon are written in order around the pentagon starting at any vertex.

D@M, so D corresponds to M.

E@N, so E corresponds to N.

F@O, so F corresponds to O.

G@P, so G corresponds to P.

H@Q, so H corresponds to Q.

The congruence statement is pentagon DEFGH@ pentagon MNOPQ.

Try This: Example 1B

Write a congruence statement for the pair of polygons.

The vertices in the first hexagon are written in order around the hexagon starting at any vertex.

110°

A

B

A@M, so A corresponds to M.

110°

140°

140°

F

B@N, so B corresponds to N.

C

110°

C@O, so C corresponds to O.

E

110°

D

N

D@P, so D corresponds to P.

110°

O

M

E@Q, so E corresponds to Q.

140°

110°

110°

F@L, so F corresponds to L.

P

140°

L

The congruence statement is hexagon ABCDEF@ hexagon MNOPQL.

110°

Q

WX @ KL

a + 8 = 24

–8 –8

a = 16

Additional Example 2A: Using Congruence Relationships to Find Unknown Values

A. Find a.

Subtract 8 from both sides.

IH @ RS

3a = 6

3a = 6

3 3

Try This: Example 2A

A. Find a.

Divide both sides by 3.

3a

I

H

a = 2

6

4b°

S

R

120°

J

30°

Q

K

c + 10°

T

ML @ YX

6b = 30

6b = 30

6 6

Additional Example 2B: Using Congruence Relationships to Find Unknown Values

B. Find b.

Divide both sides by 6.

b = 5

H @S

4b = 120

4b = 120

4 4

Try This: Example 2B

B. Find b.

Divide both sides by 4.

3a

I

H

b = 30°

6

4b°

S

R

120°

J

30°

Q

K

c + 10°

T

J @V

5c = 85

5c = 85

5 5

Additional Example 2C: Using Congruence Relationships to Find Unknown Values

C. Find c.

Divide both sides by 5.

c = 17

K @T

c + 10 = 30

c + 10 = 30

–10 –10

Try This: Example 2C

C. Find c.

Subtract 10 from both sides.

3a

I

H

c = 20°

6

90°

4b°

S

R

120°

90°

J

30°

c + 10°

Q

K

T

5-7

Transformations

Warm Up

Problem of the Day

Lesson Presentation

Pre-Algebra

5-7

Learning Goal Assignment

Learn to transform plane figures using translations, rotations, and reflections.

Vocabulary

transformation

translation

rotation

center of rotation

reflection

image

When you are on an amusement park ride,

you are undergoing a transformation. Ferris wheels and merry-go-rounds are rotations. Free fall rides and water slides are translations. Translations, rotations, and reflectionsare type of transformations.

The resulting figure or image, of a translation, rotation or reflection is congruent to the original figure.

Additional Example 1A & 1B: Identifying Transformations

Identify each as a translation, rotation, reflection, or none of these.

B.

A.

rotation

reflection

A’

C’

D’

A’

B’

B’

C’

Try This: Example 1A & 1B

Identify each as a translation, rotation, reflection, or none of these.

A.

B.

B

A

A

C

D

C

B

reflection

translation

Additional Example 1C & 1D: Identifying Transformations

Identify each as a translation, rotation, reflection, or none of these.

C.

D.

none of the these

translation

Try This: Example 1C & 1D

Identify each as a translation, rotation, reflection, or none of these.

E’

C.

D.

A’

F’

D’

A

B’

B

C’

F

C

D

none of these

rotation

E

A’

B’

C’

Draw the image of the triangle after the transformation.

A. Translation along AB so that A’ coincides with B

A

B

C

B’

A. Translation along DE so that E’ coincides with D

C’

F’

A’

D’

E’

Try This: Example 2A

Draw the image of the polygon after the transformation.

B

C

A

F

D

E

B’

C’

A’

Draw the image of the triangle after the transformation.

B. Reflection across BC.

A

B

C

B. Reflection across CD.

B’

C’

A’

F’

D’

E’

Try This: Example 2B

Draw the image of the polygon after the transformation.

B

C

A

D

F

E

C’

A’

B’

Draw the image of the triangle after the transformation.

C. 90° clockwise rotation around point B

A

B

C

D’

C’

B’

F’

E’

A’

Try This: Example 2C

Draw the image of the polygon after the transformation.

C. 90° counterclockwise rotation around point C

B

C

A

F

D

E

Draw the image of a triangle with vertices of (1, 1), (2, –2 ), and (5, 0) after each transformation.

A. 180° counterclockwise rotation around (0, 0)

Try This: Example 3A

Draw the image of a shape with vertices of (1, –2), (3, 2), (7, 3), and (6, –1) after each transformation.

A. 180° clockwise rotation around (0, 0)

y

2

x

–2

Draw the image of a triangle with vertices of (1, 1), (2, –2 ), and (5, 0) after each transformation.

B. Translation 5 units left

Try This: Example 3B

Draw the image of a shape with vertices of (1, –2), (3, 2), (7, 3), and (6, –1) after each transformation.

B. Translation 10 units left

y

2

x

–2

Draw the image of a triangle with vertices of (1, 1), (2, –2 ), and (5, 0) after each transformation.

C. Reflection across the x-axis

Try This: Example 3C

Draw the image of a shape with vertices of (1, –2), (3, 2), (7, 3), and (6, –1) after each transformation.

C. Reflection across the x-axis

y

2

x

–2