1. Section 1-7 Perimeter, Area, Circumference SPI 21B: solve equations to find length, width, perimeter and area SPI 32L: determine the area of indicated regions involving figures SPI 41A: determine the perimeter & area of 3 or 4 sided plane figures
Objectives:
find perimeter and area of rectangles and squares
find circumference and area of circles
Vocabulary
Perimeter:
the sum of the lengths of the sides of a polygon
fence around a garden
Circumference:
the distance around the outside of a circle
Area:
number of units (squared) enclosed by the perimeter or circumference

2. Some Common Formulas Perimeter: P = 4s Square Area: A = s2
s = side
Perimeter: P = 2b + 2h
Rectangle
Area: A = bh
b = base
h = height
Circumference: C = d
or C = 2r
Circle
d = diameter
r = radius
Area: A = r2

3. Real-World Connection
Fencing. Your pool is depicted in the diagram below. You want to build a fence around the deck. How much fencing will you need?
Width of pool and deck:
= 21 feet
Length of pool and deck:
= 26 feet
Solve:
P = 2w + 2L Formula
= 2(21) + 2(26) Substitute
= Simplify
You will need 94 feet of fencing.

4. Real-World and Finding Circumference
Biology. In the Pacific Northwest, a red fox has a circular home range with a radius of about 718 meters. What is the area of the home range of a red fox?
A = r Formula
A = (718) 2 Substitute
= 1,619, Simplify

5. Finding Perimeter in the Coordinate Plane
Find the perimeter of ∆ABC.
Find the length of each side.
Side AB.
|5 – (-1)| = 6
Side BC.
|6- (-2)| = 8
Side AC.
AB + BC + AC = = 24. The perimeter is 24 units.

6. Finding Area of a Rectangle
You are designing a banner for a music festival. The banner will be 4 ft wide by 7 feet high. How much material will you need?
Area of Rectangle = bh
Convert yards to feet:
7 yards = 21 feet
Substitute values into formula
A = 4(21)
= 84
You will need 84 square feet (ft2) of material.

7. Finding Area of Irregular Figures
Find the area of the figure.
Separate the figure into rectangles.
Use Area of a Rectangle Formula
A1 = 6 ∙ 2 = 12
A2 = 4 ∙ 2 = 8
Total Area = = 24 cm2
A3 = 2 ∙ 2 = 4