Similar Polygons

1
Similar Polygons
2
Similar Polygons

• In geometry, two figures that have the same shape
  are called similar.
• Two polygons are similar polygons if
  corresponding angles are congruent and
  corresponding side lengths are proportional.

A
C
F
G
H
E
D
B
ABCD FEGH
3
R
T
16
20
8
10
U
S
12
Q
P
15

• PRQ STU
• List all pairs of congruent angles
• Write the ratios of the corresponding sides in a
  statement of proportionality
• Check that the ratios of corresponding sides are
  equal

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Theorem 7.1 Perimeters of Similar Polygons

• If two polygons are similar, then the ratio of
  their perimeters is equal to the ratio of their
  corresponding side lengths.

A
D
E
F
C
B
IF ABC DEF, then DE EF FD DE EF FD
AB BC CA AB
BC CA