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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. 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
or
- P stands for the perimeter,
- r stands for the radius
- π is the mathematical constant pi (π = 3.14159265...)
- 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 center of a regular polygon to one of its vertices (or in the case of a circle, the radius), the following holds true:
- P stands for the perimeter,
- d stands for the differential operator
- r stands for the radius
- A stands for the area
See also
External links
