1. Measure the length of each side of a shape. For example, a parallelogram may have sides of 3 inches, 3 inches, 5 inches and 5 inches. 2. Add the sides together. In the example,
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you add up the distance of all the sides.
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It can be proved using Isoperimetric Inequality. https://en.wikipedia.org/. wiki/Is.
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Add up the lengths of the perimeters of all the shapes and subtract the lengths of the borders between the shapes.
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