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A square and an equilateral triangle are both examples of
regular polygons.
Another method for finding the perimeter of a regular polygon is to multiply the number of sides by the length
of one side. Let's revisit Examples 3 and 4 using this second method.
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Example 3:
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Find the perimeter of a square with each side measuring 2 inches.
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![[IMAGE]](images/square_2X2.gif)
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Solution:
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This regular polygon has 4 sides, each with a length of 2 inches. Thus we get:
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 = 4(2 in) = 8 in
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Example 4:
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Find the perimeter of an equilateral triangle with each side measuring 4 centimeters.
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![[IMAGE]](images/equilateral_triangle.gif)
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Solution:
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This regular polygon has 3 sides, each with a length of 4 centimeters. Thus we get:
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= 3(4 cm) = 12 cm
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Example 5:
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Find the perimeter of a regular pentagon with each side measuring 3 inches.
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![[IMAGE]](images/pentagon.gif)
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Solution:
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= 5(3 in) = 15 in
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Example 6:
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The perimeter of a regular hexagon
is 18 centimeters. How long is one side?
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![[IMAGE]](images/regular_hexagon.gif)
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Solution:
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= 18 cm
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Let  represent the length of one side.
A regular hexagon has 6 sides, so we can divide the perimeter by 6 to get the length of one side ().
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= 18 cm ÷ 6
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= 3 cm
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Summary:
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To find the perimeter of a polygon, take the sum of the length of each side. The
formula for perimeter of a rectangle is:  .
To find the perimeter of a regular polygon, multiply the number of sides by the length of one side.
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Interactive Math Goodies Software
