Page 664 - Basic College Mathematics with Early Integers

S E C T I O N 9.3 I PERIMETER 641

Recall that a square is a special rectangle with all four sides the same length.
The formula for the perimeter of a square is shown next:

Perimeter of a Square
Perimeter = side + side + side + side
#
= 4 side
In symbols,
P = 4s
side

side side

side

Example 3 Finding the Perimeter of a Field PRACTICE 3
Find the perimeter of a square
How much fencing is needed to enclose a square field 50 yards on a side?
tabletop if each side is 5 feet
long.
5 feet

5 feet

50 yd
Solution: To find the amount of fencing needed, we find the distance around, or
#
perimeter. The formula for the perimeter of a square is P = 4 s. We use this
formula and replace s by 50 yards.
P = 4s
#
= 4 50 yd
= 200 yd
The amount of fencing needed is 200 yards.

Work Practice 3

The formula for the perimeter of a triangle with sides of lengths a, b, and c is
given next:

Perimeter of a Triangle

Perimeter = side a + side b + side c
In symbols,
P = a + b + c
side b
side a

Answer
side c
3. 20 ft