6th Grade Math Textbook, Progress

Congruent and Similar Polygons

10-13

B

8

6

C

12

9

A 8 6 A 8 6

is similar to

The students in Class 6-B are

matting their photos (polygon A)

for gifts to their grandparents.

There are two mat sizes: 6 x 8

(polygon B) and 9 x 12 (polygon C).

How might the class describe the

photo and the mats?

Polygons A and B are congruent.

Congruent polygons have exactly

the same size and same shape.

Polygons A and C are similar.

Similar polygons have the same

shape. They may or may not

have the same size.

The corresponding parts (matching sides and

matching angles) of congruent polygons are congruent.

M
L
D
F
 
M 
D

L

KF
H
 
L 
F

K
Z
  H
J
 
K 
H

Z
M
 J

D 
Z 
J

The corresponding angles (matching angles)

of similar polygons are congruent.

PQR STU

P 
S


Q 
T


R
U

Parallelograms MLKZand DFHJare congruent and therefore similar.

Triangles PQRand STUare similar but notcongruent.

MLKZ DFHJ

Z

M

K

L

J

D

H

F

Q

R

P

36 °

26 °

118 °

T

U

S

36 °

26 °

118 °

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