1. 1.7 Perimeter, Circumference, & Area
WHAT’S IMPORTANT:
--Be able to find the perimeter & area of common plane figures.
--Be able to use a problem solving plan.

2. On the following slides, you will see the perimeter, circumference, and area formulas for some basic geometric shapes. We will use these formulas throughout the lesson.
Perimeter & circumference use units such as centimeters (cm), meters (m), inches (in), feet (ft), yards (yd), & miles (mi).
The measurements of area use units such as square centimeters (cm2), square inches (in2), & so on.

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4. 38 in.
84 sq. in.
25.12 cm.
50.24 sq. cm.
200 mm
119 sq ft.

5. 9.7 in
5.2 sq. in.
15.7 cm
19.63 sq. cm.
547.2 mm
sq. ft.

6. Example Find the perimeter & area of the rectangle shown
P = 2x + 2y
P = 2(13) + 2(4)
P =
P = 34 in.
A = xy
A = 13(4)
A = 52 in2
4 in.
13 in.

7. Example: The diameter of a circle is shown. find the radius
Example: The diameter of a circle is shown. find the radius. then use that to find the circumference and area.
r = (1/2)d
r = (1/2)(14)
r = 7in.
C = 2∏r
C = 2∏(7)
C = 2(3.14)(7)
C = in.
A = ∏r2
A = (3.14)(72)
A = (3.14)(49) = in2
14 in. F

8. Example Plot the Points & Find the area & perimeter of the triangle defined by D(1,2), E(6,2), & F(3,5)
Plot the points.
Draw the height from point F to the base DE. Label the point G
Point G has the coordinates (3,2)

9. Cont. Example...
To find the area, we need to find the lengths of the base (DE) & the height (FG)
DE = = 5
FG = = 3
A = (1/2)
A = (1/2)(5)(3)
A = (1/2)(15)
A = 7.5 sq. units

10. Plot the Points & Find the area & perimeter of the triangle defined by D(1,2), E(6,2), & F(3,5)
We need to find the lengths of all sides.
We know the base is 5 units
Now we must find the lengths of EF & DF.

11. Plot the Points & Find the area & perimeter of the triangle defined by D(1,2), E(6,2), & F(3,5)
Add to find the perimeter
Perimeter = units

12. find the area of the figure below
Draw a horizontal line to separate the figure into 3 non-overlapping figures: a rectangle & 2 squares.

13. Find each area by adding
Area of the Rectangle
A = bh
A = (15)(5)
A = 75
Area of the Square
A = s 2
A = (5)2
A = 25
Add the areas
A =
A = 125 ft 2
Therefore the area of the figure is 125 ft 2.