1. Do Now: 1)
x = 8 2)
x = 14 3)
x = 6, –6 4)
x = 9, –6

2. Similar Triangles are marked by their congruent angles.P Q R
30o
60o
~ symbol for “is similar to”
ABC ~ RPQ
Use proportions to find the missing sides of triangles.
AB ~ QR
BC ~ PQ
AC ~ PR

3. Finding Similar Sides 1) 2) 3) 4) MN ~ ____ M N P Q R S AB ~ ____ A BC D E F QR DE 3)
ST ~ ____ S T U V W X 4)
XY ~ ____ X Y Z G H J VW GJ

4. 2.) MNO is similar to QRS. What is the length of RQ?
Examples: r 18 7 9
1.) Find the value of r.
9r = 126
r = 14
2.) MNO is similar to QRS. What is the length of RQ? DE S 6 x 9 Q R O M y 12 7 N
12x = 63
x = 5.25
Find the value of y.
9y = 72
y = 8

5. Find the missing side. 4) 3) 72 = 9x 8 = x 5) 6) 3y = 36 y = 12C A F S H
x + 6 x 12 30 R S T x 6 10 3) N L M 15 9 12
30x = 12x + 72
18x = 72
x = 4 and x + 6 = 10
72 = 9x 8 = x 5) W X Y D O G 3 6 y F E D y 5 x A B 10 14 6 C 6)
3y = 36
y = 12
10x = 70
x = 7
10y = 30
y = 3