Page 666 - Basic College Mathematics with Early Integers

S E C T I O N 9.3 I PERIMETER 643

Now that we know the measures of all sides of the room, we can add the measures
to find the perimeter.
9 ft
3 ft
10 ft 6 ft
7 ft

15 ft
perimeter = 10 ft + 9 ft + 3 ft + 6 ft + 7 ft + 15 ft
= 50 ft

The perimeter of the room is 50 feet.
Work Practice 6

Example 7 Calculating the Cost of Wallpaper Border PRACTICE 7
A rectangular lot measures
A rectangular room measures 10 feet by 12 feet. Find the cost to hang a wallpaper 60 feet by 120 feet. Find the
border on the walls close to the ceiling if the cost of the wallpaper border is cost to install fencing around
$1.09 per foot. the lot if the cost of fencing is
Solution: First we find the perimeter of the room. $1.90 per foot.
P = 2l + 2w
#
#
= 2 12 ft + 2 10 ft Replace l with 12 feet and w with 10 feet.
= 24 ft + 20 ft
= 44 ft
The cost of the wallpaper is
#
cost = $1.09 44 ft = 47.96
The cost of the wallpaper is $47.96.
Work Practice 7

Objective Using Formulas to Find Circumferences

Recall from Section 4.3 that the distance around a circle is called the circumference.
This distance depends on the radius or the diameter of the circle.
The formulas for circumference are shown next:

Circumference of a Circle

radius
center
diameter

#
# #
Circumference = 2 p radius or Circumference = p diameter
In symbols,
C = 2pr or C = pd,
22
where p L 3.14 or p L . Answer
7
7. $684