The shape and the name of a polygon both depend on the number of sides it has. A polygon with 10 sides is a decagon. Decagons can be either regular or irregular. Regular decagons have 10 equal sides and 10 equal interior angles; irregular decagons have sides and angles of varying measurements. Finding the perimeter of a decagon means finding the measurement around the polygon, which depends on the lengths of each sides.
Instructions
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1
Measure each side of an irregular decagon. For an example, let the sides measure 2, 1.5, 1.5, 2, 3, 4, 4, 3, 1 and 2 inches.
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2
Add the measurements together to find the perimeter --- the measurements in Step 1 together equal 24 inches.
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3
Multiply one side length of a regular decagon and multiply it by 10. For an example, a regular decagon where each side length is 3 inches has a perimeter of 3 inches times 10, which equals 30 inches.