Transcript Using Similar Figures - Gateway School District

COURSE 2 LESSON 5-6
Using Similar Figures
ABC is similar to
DEF. Find the value of c.
c
6
=
18
9
Write a proportion.
9c = 18 • 6
Write the cross products.
108
9c
=
9
9
Divide each side by 9.
c = 12
Solve for c.
5-6
COURSE 2 LESSON 5-6
Using Similar Figures
A 5-ft person standing near a tree has a shadow 12 ft long. At
the same time, the tree has a shadow 42 ft long. What is the height of
the tree?
Draw a diagram like the one at the right.
Let x represent the height of the tree.
x
42
=
5
12
Write a proportion.
12x = 5 • 42
Write the cross products.
12x 5 • 42
= 12
12
Divide each side by 12.
x = 17
1
2
Simplify.
1
The height of the tree is 17 2 ft.
5-6
COURSE 2 LESSON 5-6
In the figure below,
Using Similar Figures
JKL ~
1. Which angle besides
XYZ.
K has measure 29°?
Y
2. Find YZ.
9
3. A 4-ft-tall person standing near a telephone pole has a shadow 3 ft long.
At the same time, the telephone pole has a shadow 18 ft long. What is the
height of the telephone pole?
24 ft
5-6