7.2 – Similar Polygons
Learning Target 1: To be able to use properties to identify similar polygons. Learning Target 2: To be able to solve proportions using the properties of similar polygons.
• Similar: figures that have the same SHAPE but not necessarily the same size.
• Similar Polygons have… • corresponding angles that are congruent • corresponding sides that are proportional
Name the Corresponding Angles… (CONGRUENT)
Name the Corresponding Sides… (PROPORTIONAL)
Similar Polygons…
Similarity Statement…
Scale Factor…
• Scale Factor: The ratio of the lengths of the corresponding sides of 2 similar polygons.
ABC XYZ
A
B
C
6
X
Y
Z
3
Given: 6
23
3 1
6 2
ABC to XYZ is
XYZ to ABC is
Scale Factor…
Are We Similar??
Corresponding angles congruent? Corresponding sides proportional? If so… What is the scale factor? Write a similarity statement.
Are We Similar??
Corresponding angles congruent? Corresponding sides proportional? If so… What is the scale factor? Write a similarity statement.
Scale Factor…
• When polygons are similar, the scale factor can be used to find the values of variables.
Determine the scale factor. Then set up a proportion and solve for the unknown variable.
Scale Factor…
Determine the scale factor. Then set up a proportion and solve for the unknown variable.
Scale Factor…
Determine the scale factor. Then set up a proportion and solve for the unknown variable.
Perimeters of Similar
Polygons…
If ABCDE ~ RSTUV… find the scale factor of ABCDE to RSTUV and the perimeter of each polygon.
Perimeters of Similar
Polygons…
Perimeters of Similar
Polygons…
If ABCDE ~ RSTPQ… find the scale factor of ABCDE to RSTPQ and the perimeter of each polygon.
Pg. 469
#1, 2, 12 – 15,
18 – 21, 23, 24,
35, 36
Homework
