1. 8-2 Similar Polygons Objective: To identify and apply similar polygons
4/4/17
8-2 Similar Polygons
Objective: To identify and apply similar polygons
SIMILAR:
Corresponding angles are congruent
Corresponding sides are proportional
SIMILAR RATIO: the ratio of the lengths of corresponding sides

2. Corr. sides are proportional m B = GH = FG CD x
Ex: ABCD EFGH B C
m E = ? F G
m E = m A = o o
Corr. s congruent A D E H
AB = AD
EF ?
EF EH
Corr. sides are proportional
m B =
GH = FG
CD x
127°
x = BC

3. ABC FED with a similarity ratio of ¾ or 3:4
Match up the biggest side of one Δ to the biggest side of the other, then the next biggest sides, and finally the smallest sides.
Ex: If similar, write a similarity statement and give the similarity ratios.
AC = 18 = B E FD
AB = 15 = 3 A C D F FE
BC = 12 = 3 ED
ABC FED with a similarity ratio of ¾ or 3:4

4. LM = ON Corr. Sides of cong. L 5 M Q 6 R QR TS polygons are prop.
Isosceles Trapezoids
Ex: LMNO QRST O N T x S
Find the value of x
LM = ON Corr. Sides of cong. L M Q R
QR TS polygons are prop.
5 = Substitution
6 x
5x = Cross product property
x = 2.4
Find SR to nearest tenth
5 = 3.2 y
y = 3.84  3.8

5. GOLDEN RATIO: in any golden rectangle, the length : width 1.618:1
GOLDEN RECTANGLE: a rectangle that can be divided into a square and a rectangle that is similar to the original rectangle
GOLDEN RATIO: in any golden rectangle, the length : width :1
a + b = a
a b

6. Assignment: Page 426 #13 – 17, 21 – 28