Three sides define a triangle, and the measurements of those three sides define its perimeter. The perimeter of any two-dimensional closed object is the distance around the object and a measurement of the space the object occupies. Triangles belong to a special class of two-dimensional shapes called polygons, in which each side is a straight-line segment. Calculating the perimeter of any polygon involves measuring and adding the sides. Because triangles only have three sides, you can easily find their perimeters.
Instructions
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1
Measure the length of a side from vertex to vertex with a ruler. For this example, allow the side to be 3 inches.
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2
Repeat with the other two sides. In this example, the other two sides measure 4 and 5 inches.
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3
Add all the side measurements together. Concluding this example, adding 3, 4 and 5 inches together equals 12 inches.