Perimeter of Polygons

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Perimeter of Polygons

• By Sara Gregurash

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Perimeter

• Perimeter is the distance (length) around the
  outside of a polygon. To find the perimeter of a
  polygon, take the sum of the distance along each
  of its sides (P sum of all the sides). It is
  important to study perimeter because it makes
  everyday life easier.
• For example, the perimeter was needed for a fence
  that was placed around a backyard. The amount of
  fence needed to enclose the yard had to be
  figured out, which is the perimeter. You have to
  know how much fence you need in order to buy the
  fence (a length in feet, yards, or meters) at a
  store.
• This presentation will show you how to figure out
  the perimeter of polygons. I have used smaller
  units like centimeters and inches because these
  polygons are smaller than a fence.

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Perimeter of a triangle

• To find the perimeter of a triangle you have to
  add up the three sides. The equation looks like
  this
• P s s s
• Using the triangle below, the sides have a length
  of 8 centimeters, 6 centimeters, and 5
  centimeters.
• P s s s
• P 8 cm 6 cm 5 cm
• P 19 cm

8 cm
5 cm
6 cm
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Perimeter of a square

• The equation to find the perimeter of a square is
  P s s s s
• For the square below the length of each side is 4
  inches.
• P s s s s
• P 4 in 4 in 4 in 4 in
• P 16 in

4 in
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Perimeter of a rectangle

• To find the perimeter of a rectangle you have to
  use the formula, P 2l 2w ( l is the length
  and w is the width).
• The length of the rectangle below is 9 inches and
  the width is 5 inches.
• P 2l 2w
• P 2(9 in) 2(5 in)
• P 18 in 10 in
• P 28 in

5 in
9 in
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Perimeter of a parallelogram

• To find the perimeter of a parallelogram, you
  have to use the following equation
• P 2l 2w
• Using the parallelogram below, the length is 20
  centimeters and the width is 7 centimeters.
• P 2l 2w
• P 2(20 cm) 2(7 cm)
• P 40 cm 14 cm
• P 54 cm

7 cm
20 cm
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Perimeter of regular polygons

• Regular polygons have all sides that are equal
  length and all angles are equal.
• A square and an equilateral triangle are examples
  of regular polygons. Another way to find the
  perimeter of a regular polygon is to multiply the
  number of sides by the distance along one side.
• Here is an example of a regular polygon called a
  hexagon (6 sided figure). The equation to find
  the perimeter of a hexagon is
• P 6 length of a side
• The perimeter of the hexagon below with sides
  that have a length of 4 inches is
• P 6 length of a side
• P 6 4 in
• P 24 in

4 in
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Websites

• Here are links to lessons, exercises, and
  worksheets about area and perimeter of polygons.
  You can practice your skills from these sites.
• Perimeter Lesson and Exercise
• Exercise on Area and Perimeter
• Area and Perimeter Worksheet

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Have fun with perimeter

• These two websites have fun activities to do that
  are related to polygon shapes and the area and
  perimeter of polygons.
• Polygon Crossword
• Polygon Word Search

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Practice your perimeter skills

• Now, that you are familiar with calculating the
  perimeter of polygons its time for my worksheet.
  This will allow you to see how well you learned
  the material. Good luck!
• Here are the answers to my worksheet.

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Test Time

• This is your chance to see how much you have
  learned from all three of my power point
  presentations.
• Test Your Knowledge
• The Answers