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For other uses, see Perimeter (disambiguation).

The perimeter is the distance around a given two-dimensional object. The word perimeter is a Greek root meaning measure around, or literally "around-measure".

Contents

[edit] Practical uses

Calculations of perimeter and area have considerable practical applications. Perimeter is used in calculating the border of an object such as a yard or flowerbed when a fence or other border is being installed around the edges. Area is used when all the area inside of a perimeter is being covered with something, such as a yard being covered with sod or fertilizer.

In military usage, the term perimeter defines a geographic area of importance, such as a physical installation or defensive work, but can also refer to a theoretical construct such as an all-round defense formed by a small group of soldiers, the purpose of which is mutual protection of each other rather than defence of actual territory.

[edit] Formulas

[edit] Polygons

As a general rule, the perimeter of a polygon can always be calculated by adding all the length of the sides together. So, the formula for triangles is P = a + b + c, where a, b and c stand for each side of it. For quadrilaterals the equation is P = a + b + c + d or P = a + b + a + b. For equilateral polygons, P = na, where n is the number of sides and a is the measure of the side.

[edit] Circles

For circles the equation is

P = 2πr

or

P = πd

where P is the perimeter, r is the circle's radius, π is the mathematical constant pi, and d is the circle's diameter.

[edit] In general

If r is considered to be the distance from the center of a regular polygon to one of its vertices (or in the case of a circle, the radius), the following holds true:

P = \frac{dA}{dr}

[edit] See also

[edit] External links

Look up Perimeter in
Wiktionary, the free dictionary.