Perimeter of shapes

Definition: 

The distance that surrounds a two dimensional shape is known as “Perimeter.”  

Simply, we can say that ‘The Perimeter is the length of the outline of a shape. 

In the below figure if we start measure from the point A and move along the line segments and reach again the point A.
We have made a complete round of the shape, and the distance is equal to covered by shape.

The distance is known as the  Perimeter of the shape.

       Distances from A to A is shown in above figure from 

                                A to B

                                B to C

                                C to D

                        and   D to A

      Distance from,    

             A to B, is  AB equal to  5 cm,

             B to C  is BC equal to  3 cm,

             C to D  is CD equal to  5 cm,               

    and   D to A  is DA equal to  3 cm. 

 Therefore, total distance of the shape or distance   

surrounds by shape is, or perimeter is

                        AB + BC + CD + DA,

                      = 5 + 3 + 5 + 3

      perimeter  = 16 cm.

Example: The perimeter of this pentagon is,

                    AB + BC + CD + DE + EA

                       = 4 + 4 + 4 + 4 + 4

                       = 20 cm.

Perimeter Formula’s

1.                              Triangle

       Perimeter of a triangle = AB + AC + BC

                                        = a + b + c

2.                     Equilateral triangle

Perimeter of an equilateral triangle = AB + AC + BC

                                                   = a + a + a

                                                   = 3 x a
 Perimeter of an equilateral triangle = 3 x length of a side.
                                                   

3. Rectangular   

 Perimeter of a rectangular = Width + Height + Width + Height  
                                      = 2(Width + Height)

Perimeter of a rectangular = 2 x (W + H) 
               W = Width,  and   H = Height 

4.                 Perimeter of a Square

 Perimeter of a Square = AB + BC + CD + DA

                                 = a + a + a + a

                                 = 4 x a

Perimeter of a Square = 4 x Length of a side

5.                   Perimeter of a Circle

       Perimeter of a circle is called Circumference.

               Perimeter of a circle = 2𝜋r

                                           = 2𝜋 x radius