Perimeter


Perimeter

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".

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.

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 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.

Circles

For circles the equation is: P = 2 pi ror: P = pi d

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

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}
* P stands for the perimeter,
* d stands for the differential operator
* r stands for the radius
* A stands for the area

See also

* Isoperimetric inequality
* Circumference
* Pythagorean Theorem
* Wetted perimeter

External links


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