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Geometry
6.1: Use similar polygons
Objective: SWBAT use proportions to identify similar polygons.
Similar Polygons
Two polygons are similar if corresponding
angles are congruent and corresponding side
lengths are proportional.
A similarity statement is written to show the
corresponding sides and angles.
PQRS ~ ABCD means these two polygons are similar; P corresponds to A,
Q corresponds to B, and so on.
Similar Polygons
If two polygons are similar, then the ratio of
the lengths of two corresponding sides is
called the scale factor.
Example of scale factor:
X
A
B
4
C
Y
8
Z
Given
Theorem 6.1: Perimeter of similar
polygons
If two polygons are similar, then the ratio of
their perimeters is equal to the ratio of their
corresponding side lengths.
Corresponding lengths in similar polygons: If
two polygons are similar, then the ratio of any
two corresponding lengths in the polygons is
equal to the scale factor of the similar
polygons.
Example 1:
Example 2:
Hint: Draw a picture
Example 3:
Example 4:
Example 5:
Example 6:
Example 7:
Homework
Page 362 #4-12 evens