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Geometry Section 7-1B Geometry Section 7-1B

Similar PolygonsSimilar Polygons

Page 468Page 468You will need a calculator You will need a calculator

with sin/cos/tan in 2 with sin/cos/tan in 2 weeks.weeks.

Freshmen - TI 30 XII S Freshmen - TI 30 XII S recommended. Around $15. You’ll recommended. Around $15. You’ll

need it for Alg. II.need it for Alg. II.

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Similar Polygons:Similar Polygons:The symbol ~ means “is similar to”. ABCDE ~ MNOPQ

means that two pentagons are similar and that segment AB corresponds to with segment MN, etc. The order of the

letters in the similarity correspondence indicates the corresponding parts.

Name all pairs of congruent corresponding angles, and write proportions using the pairs of corresponding sides.

Pg.468

AM, BN, CO, DP, EQ

Side Lengths:

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Try It:Try It:Write the similarity correspondence between each pair of

figures. Name all pairs of congruent corresponding angles and write proportions using the pairs of corresponding

sides.

Pg.469

EFG ~ JIHEJ, FI, GH

EF FG GE 1 JI IH HJ 2

= = =

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Try It:Try It:Write the similarity correspondence between each pair of

figures. Name all pairs of congruent corresponding angles and write proportions using the pairs of corresponding

sides.

Pg.469

QRST ~ YXWVQY, RX, SW, TV

QR RS ST TQ 3 YX XW WV VY 1= = = =

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Try It:Try It:You can use the information for similar polygons to find

unknown angle measure and side lengths in similar polygons.

Pg.470

EFGH ~ KNML

Find the measures of angles E, G, and N

E = 67o, G = 107o, N = 43o

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Try It:Try It:You can use the information for similar polygons to find

unknown angle measure and side lengths in similar polygons.

Pg.470

EFGH ~ KNML

Find x, y and z

x = 14, y = 15, z = 25

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Try It:Try It:You can use the information for similar polygons to find

unknown angle measure and side lengths in similar polygons.

Pg.470

EFGH ~ KNML

What is the similarity ratio of KNML to EFGH?

5/2

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Exercises:Exercises:

Name all pairs of congruent corresponding angles, and write proportions using the pairs of corresponding sides.

#1

Pg.471

AE, BF, CG, DH

Side Lengths:

ABCD ~ EFGH

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Exercises:Exercises:

2-8

Pg.471

IJKL ~ MNOP

What is the similarity ratio of IJKL to MNOP?

mN = 106o

mL = 49o

x = 9y = 15

z = 12

2/3

What is the similarity ratio of MNOP to IJKL? 3/2

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Exercises:Exercises:

11-13

Pg.471

ABC ~ DEF. The similarity ratio of ABC to DEF is 7/3.

If AB = 27, find DE. 11.57

If EF = 14, find BC. 32.67

Find DF/AC. 3/7

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Exercises:Exercises:

#14

Pg.471

The coordinates of Rectangle WXYZ are W(1,1), X(5,1), Y(5,4) and Z(1,4).

Rectangle STUV with lower left-hand vertex S(2,7) is similar to WXYZ and its

sides are parallel to the corresponding sides of WXYZ. Find the coordinates of T, U

and V for the similarity ratio.

STWX

= 4

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Exercises:Exercises:

#15

Pg.471

The coordinates of Rectangle WXYZ are W(1,1), X(5,1), Y(5,4) and Z(1,4).

Rectangle STUV with lower left-hand vertex S(2,7) is similar to WXYZ and its

sides are parallel to the corresponding sides of WXYZ. Find the coordinates of T, U

and V for the similarity ratio.

STWX

= 1

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Exercises:Exercises:

#16

Pg.471

The coordinates of Rectangle WXYZ are W(1,1), X(5,1), Y(5,4) and Z(1,4).

Rectangle STUV with lower left-hand vertex S(2,7) is similar to WXYZ and its

sides are parallel to the corresponding sides of WXYZ. Find the coordinates of T, U

and V for the similarity ratio.

STWX = ½

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Exercises:Exercises:

#17

Pg.471

1 inch = 156 miles:If Boston and Houston are 10 ¼ in. apart on a map, what is

the actual distance between the 2 cities?

1599 miles

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Exercises:Exercises:

#18

Pg.471

1 inch = 156 miles:If Los Angeles and New York are actually 2451 miles apart,

how far apart are they on the map?

15.71 inches.

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Homework: Practice 7-1BQuiz Friday