Perimeter
Perimeter is defined as the distance around an object. For a polygon (an object with many sides) the
perimeter is the sum of the lengths of the sides. For a circle the distance around the outside is called
the circumference.
Rectangle
P = 2l + 2w
Square
Triangle
P = 4s
P=a+b+c
Circle
Circumference: C = 2r
or C = d
Example 1: Finding Perimeter and Circumference
Find the perimeter or circumference as indicated. Use 3.14 for .
a. Perimeter:
b. Perimeter:
Solution:
a.
P=a+b+c
Add the lengths of the sides
P = 4 in. + 2 in. + 5 in. = 11 in
The perimeter is 11 inches
b.
P = 2 l + 2w
Substitute l = 5.5 ft and w = 3.1 ft
P = 2(5.5 ft) + 2(3.1 ft) = 11 ft + 6.2 ft = 17.2 ft
The perimeter is 17.2 feet
c.
C = 2r
Substitute r = 6 cm and leave  in your answer
C = 2()(6 cm) = 12 cm
The circumference is 12 cm
The Academic Support Center at Daytona State College (Math 55 pg 1 of 1)
c. Circumference