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." Perimeter can be calculated for any two dimensional object, with the right formula.

Practical uses

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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

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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 side length.

Circles

For circles the equation is

$$

P = 2 \cdot \pi \cdot r or

$$

P = d \cdot \pi

• $P$ stands for the perimter,
• $r$ stands for the radius
• $\backslash pi$ is the mathematical constant pi ($\backslash pi=3.14159265...$)
• $d$ stands for the circle's diameter

(The dot means multiply or times)

See also

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See also:

• Isoperimetric Theorem
• Circumference
• Pythagorean Theorem
• Wetted perimeter

Perímetre | Umfang | Perímetro | Périmètre | Perimetro | Perímetro | Perimeter | Периметр | Perimeter | 周界

Elementary geometry