The document discusses using proportions with similar polygons. It defines similar polygons as those where corresponding angles are congruent and corresponding lengths are proportional. It introduces the scale factor as the ratio of lengths of corresponding sides in similar polygons. It states that the ratio of perimeters of similar polygons equals the ratios of corresponding side lengths. Finally, it notes that if two figures are congruent, then they are similar, and if two figures are similar, then the ratio of corresponding sides is the scale factor.

1. 6.3 Use proportions November 15, 2011
Bellwork
HW pg. 376 #4­12 evens, 20­28 evens 1

2. 6.3 Use proportions November 15, 2011
6.3 Similar Polygons
B C Similar polygons: corresponding angles are congruent and
F
corresponding lengths are proportional
G
A D <A ≅ <E ...
E H
AB BC
-- = --
∴ ABCD ~ EFGH EF FG ...
HW pg. 376 #4­12 evens, 20­28 evens 2

3. 6.3 Use proportions November 15, 2011
Scale Factor: ratio of lengths of corr. sides in similar polygons
HW pg. 376 #4­12 evens, 20­28 evens 3

4. 6.3 Use proportions November 15, 2011
HW pg. 376 #4­12 evens, 20­28 evens 4

5. 6.3 Use proportions November 15, 2011
Perimeters of Similar Polygons Theorem: If 2 polys are ~,
then the ratio of perimeters = the ratios of corr. side lengths
If KLMN ~ PQRS, then KL+LM+MN+NK = KL = LM = MN= NK
K L PQ+QR+RS+SP PQ QR RS SP
P Q
N M S R
HW pg. 376 #4­12 evens, 20­28 evens 5

6. 6.3 Use proportions November 15, 2011
Similarity & Congruence: If 2 figures are ≅, then they are ~.
If 2 figures are ~, then the ratio of corr. sides = scale factor
HW pg. 376 #4­12 evens, 20­28 evens 6

7. 6.3 Use proportions November 15, 2011
HW pg. 376
#4-12 evens,
20-28 evens
HW pg. 376 #4­12 evens, 20­28 evens 7