Perimeter

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This article is about the distance around an object. For the freeway around Atlanta, Georgia, see Interstate 285.

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".

1 Practical uses
2 Formulas
3 See also
4 External links

Practical uses

Perimeter and area play a great role in today's world. 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.

Formulas

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 Failed to parse (Missing texvc executable; please see math/README to configure.): P=a+b+c , where Failed to parse (Missing texvc executable; please see math/README to configure.): a , Failed to parse (Missing texvc executable; please see math/README to configure.): b

and Failed to parse (Missing texvc executable; please see math/README to configure.): c
stand for each side of it. For quadrilaterals the equation is Failed to parse (Missing texvc executable; please see math/README to configure.): P=a+b+c+d

. For equilateral polygons, Failed to parse (Missing texvc executable; please see math/README to configure.): P=na , where n is the number of sides and a is the measure of the side.

Circles

For circles the equation is

Failed to parse (Missing texvc executable; please see math/README to configure.): P = 2 \cdot \pi \cdot r

Failed to parse (Missing texvc executable; please see math/README to configure.): P = d \cdot \pi

Failed to parse (Missing texvc executable; please see math/README to configure.): P

stands for the perimeter,

Failed to parse (Missing texvc executable; please see math/README to configure.): r

stands for the radius

Failed to parse (Missing texvc executable; please see math/README to configure.): \pi

is the mathematical constant pi (Failed to parse (Missing texvc executable; please see math/README to configure.): \pi=3.14159265...

)

Failed to parse (Missing texvc executable; please see math/README to configure.): d

stands for the circle's diameter (twice the radius of a circle)

(The dot means multiply or times)

In General

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

Failed to parse (Missing texvc executable; please see math/README to configure.): P = \frac{dA}{dr}