Sec 1'7 Find Perimeter, Circumference, and Area

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Sec 1.7 Find Perimeter, Circumference, and Area

• Perimeter is the distance around a figure
• Circumference is the distance around a circle
• Perimeter and circumference are measured in units
  of length, such as meters (m) and feet (ft).
• Area is the amount of surface covered by a
  figure. It is measured in square units, such as
  square meters (m2) and square feet (ft2)

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Formulas for Perimeter P, Area A, and
Circumference C
Square Side length s P 4s A s2
Rectangle Length l and width w P 2l 2w A lw
Triangle Side lengths a, b, and c, base b, and
height h P a b c A ½ bh
Circle Diameter d and radius r C ? d 2? r A
? r2
Pi (?) is the ratio of a circles circumference
to its diameter
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EXAMPLE 1
Find the perimeter and area of a rectangle
SOLUTION
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EXAMPLE 2
Find the circumference and area of a circle
SOLUTION
Then find the circumference and area.
Use 3.14 to approximate the value of p.
The circumference is about 28.3 cm. The area is
about 63.6 cm2 .
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EXAMPLE 3
Standardized Test Practice
SOLUTION
First draw triangle QRS in a coordinate plane.
Find the side lengths. Use the Distance Formula
to find QR and RS.
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EXAMPLE 3
Then find the perimeter.
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for Examples 3 and 4
GUIDED PRACTICE
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for Examples 3 and 4
GUIDED PRACTICE
SOLUTION
Use the distance formulas to count EG, FG and EF
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Then find the perimeter
GUIDED PRACTICE
To find the area of the triangle, you need the
base and height, but they have to form a right
angle. In this problem, look for a base and
height that you can count, which would be segment
EG and the line from point F to segment EG
Substitute 6 for height and 4 for base
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Converting Units

• When you convert inches to feet, you simply
  divide the number of inches by 12 because there
  are 12 in to 1 ft.
• HOWEVERwhen converting in2 to ft2 , you must
  square the number of inches in a foot,
• so 1 ft2 would be 144 in2

Ex. 13 ft2 _____ yd2
Since there are 3 ft in 1 yd, there are 9 ft2 in
1 yd2
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Bkwkp 52-544-32 even, 40, 44