In Geometry, the word Perimeter is used either to indicate path or length. The word Perimeter comes from two Greek words "PERI" (which means around) and "METER"(which means measure). A Perimeter of any figure can be defined in various ways.
  • A Perimeter of any polygon is the total distance along the outside of the polygon. 
  • A Perimeter of a figure is total length of all its sides.
  • A Perimeter is the length of the boundary of a figure.
  • A Perimeter is the length of the outline of a shape.

Computing Perimeter has many practical applications. For example, it could be used to find out the revolutions of a wheel, length of a fence surrounding a yard or garden, the amount of wool wound around a spool is related to perimeter of the spool, the distance ran by a jogger around a path, etc.

Perimeter formulas (small description of triangle and rectangle and their formulas and diagram)

Perimeter of Regular Shapes:

The perimeter of regular polygons (a figure which has all of its sides equal and all angles equal) is given by the product of number of sides with length of its side.

Perimeter of few regular polygons is given below with diagrams and formulas.

Let "s" be the length of each side of these figures.

Equilateral triangle:
Equilateral Triangle
Perimeter = s + s + s
Perimeter = 3 x s

Rhombus Sides
Perimeter = s + s + s + s
Perimeter = 4 x s

Square Sides
Perimeter = s + s + s + s 
Perimeter = 4 x s

Regular pentagon:
Regular Pentagon
Perimeter = s + s + s + s + s
Perimeter = 5 x s

Regular hexagon:
Regular Hexagon
Perimeter = s + s + s + s + s + s
Perimeter = 6 x s

Perimeter of other Shapes:

Other shapes like Rectangle, Triangle, Parallelogram, Trapezium, Kite also have Perimeter. The following are the diagrams and formulas for the same.

Perimeter of Rectangle
Perimeter = 2(l+b)
l = length of the rectangle
b = width of the rectangle

Perimeter of Triangle
Perimeter = a + b + c
Where,  a, b, c are lengths of each side.

Perimeter of Parallelogram
Perimeter = 2(a+b)
a = length of the parallelogram
b = width of the parallelogram

Perimeter of Trapezium
Perimeter = a + b + c+ d
a, b, c are lengths of each side.

Perimeter of Kite
Perimeter = 2(a+b)
a is the length of each side in one pair
b is the length of each side in the other pair

The perimeter of a circle is generally known as the circumference.
Perimeter of Circle
Circumference of a Circle = 2pi r,  where: r is the radius of circle
Circumference of a Circle = pi d,  where: d is the diameter of circle.

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