chapter 7.2 similar polygons. vocabulary similar – two polygons are similar if – 1)...

Chapter 7.2 Similar Polygons

Vocabulary

• Similar – Two polygons are similar if– 1) Corresponding angles are congruent– 2) Corresponding sides are proportional

stands for similar~

Vocabulary

• Similarity ratio – the ratio of the lengths of corresponding sides of similar figures

• Example:

A

B C

D

E F

FD

CA

EF

BC

DE

AB

DEFABC ~

Vocabulary

• Golden rectangle – rectangle that can be divided into a square and a rectangle that is similar to the original rectangle

A B

CD F

E

ABCD is a rectangleADFE is a square

BCFEABCD ~

Vocabulary

• Golden ratio – the ratio of the length of a golden rectangle to its width. The value of the golden ratio is or about 1.62

2

51

Determining Similarity

• Determine whether the triangles are similar. If they are, write a similarity statement and give the similarity ratio

• Given: Corresponding angles congruent• Are the corresponding sides proportional?

A

B

C D

E

F18

1215

24

1620

DE

AB

EF

BC

DF

AC

Answer

• with similarity ratio of or 3:4 DEFABC ~4

3

ABCD~EFGH complete each statement

Em

AD

EF

AB

A

B C

D

E

F G

H

53

127

LMNO~QRST

• Find the value of xO

N

L M

T S

Q R

2

5

X

6

Classwork/Homework

• Pgs 375-376 1-16, 21-28