Name _________________________________ Period_________ Date________________
Similar Triangles
Figures that have the same shape but not necessarily the same size are similar figures. The symbol
is similar to. If two triangles are similar, then their corresponding sides are proportional.
Example:
B
L
5
I
10
O
(a) BOX
means
D
12
X
y
LID . Find the value of y, using proportions.
(b) Let mLD  13. Find the measure of BX.
mBO

mLI
10

5
mBO mOX

Corresponding sides are proportional.
mLI
mID
10 y

5 12
10(12)  5 y Solve, using cross products.
mBX
mLD
mBX
13

130  5 mBX
120  5 y
24  y

26  mBX
Name _________________________________ Period_________ Date________________
Similar Triangles
Figures that have the same shape but not necessarily the same size are similar figures. The symbol
is similar to. If two triangles are similar, then their corresponding sides are proportional.
Example:
B
L
5
I
10
O
(a) BOX
means
y
D
12
X
LID . Find the value of y, using proportions.
mBO mOX

Corresponding sides are proportional.
mLI
mID
10 y

5 12
Solve, using cross products.
10(12)  5 y
120  5 y
24  y
(b) Let mLD  13. Find the measure of BX.
mBO

mLI
10

5
mBX
mLD
mBX
13

130  5 mBX
26  mBX

Similar Triangles (page 2)
Given ABC
your work.
DEF , solve each of the following. Show
1. Find b if e = 4, a = 9, and d = 12.
C
F
a
B
b
d
e
A
c
E
D
f
4. Find e if d = 30, a = 10, and b = 6.
2. Find c if f = 9, b = 8, and e = 12.
3. Find d if a = 6, f = 7, and c = 5.
Similar Triangles (page 2)
Given ABC
your work.
C
DEF , solve each of the following. Show
1. Find b if e = 4, a = 9, and d = 12.
F
a
B
b
c
d
e
A
E
f
4. Find e if d = 30, a = 10, and b = 6.
2. Find c if f = 9, b = 8, and e = 12.
3. Find d if a = 6, f = 7, and c = 5.
D