Section 8.3 Similar Polygons

Similar Figures

• Two figures that have the same shape are similar–Not necessarily the same size!–Enlarging and shrinking

Real life example of Similarity

Similar Polygons• Two polygons are similar if:–corresponding angles have the same

measure–corresponding sides are in proportion–Symbolic notation for similarity: ~

Congruent vs. Similar

Congruence Similarity

Similarities

Figures are the exact same size and shape

Corresponding sides are equal

Corresponding angles are equal

Figures have the same shape but not necessarily the same size.

Corresponding sides are in proportion

Corresponding angles are equal

Both have corresponding angles that are equal.Same shape of the object

Both have a symbolic notation

Example of Similar Polygons

ABCD ~ EFGH

________ = _________ =__________=_________

Similarity Statement

Statement of Proportionality

How to determine similarity:

• Are corresponding angles equal?• Are corresponding sides in

proportion?–Are the ratios the same?

Are they similar?

Are they similar?

Scale Factor• Ratio of the lengths of two

corresponding sides of similar figures.• Corresponding sides change by

the same scale factor. –What does this mean?

It means that all the sides of the small figure are multiplied by the same number to obtain the lengths of the corresponding sides of the large figure.

Find the scale factor.

Find the scale factor.