How to find the perimeter of plane figures. (Maths lesson)

  Have you heard the word ‘Perimeter’???  

             Perimeter is the distance around the edges of a particular shape. Finding the perimeter simply means adding the lengths of all the sides of the shape.  

Some of the shapes are shown below. 

                                              Source

We can find the perimeters of all these shapes. Let's try to find the perimeter in the given figures. 

In this, the lengths of all the sides are given as 2 cm.

P= 2+2+2+2

   = 8cm

So the perimeter in the given square is 8cm. we can find this in a easy way.

P= 2 x 4

    = 16 cm

Let's find the perimeter of this rectangle.

The lenths of the two parallel sides are equal.

P = 2+2+4+4 / (2 x 2) + ( 4 x 2)

   = 12 cm

Let's find in this triangle.

P = 3+3+3 / (3 x 3)

   = 9 cm

Like this, you can find the perimeter of any shape if the lengths are given. Now you may be confused of finding the primeter of a circle. 

The way of finding the perimeter of a circle is different from the way of finding the perimeters of other shapes.

Normally we don't say the perimeter of a circle. We call it as the 'Circumfrence'.

Let's see how to find the circumference of a circle. 

First of all let's learn the parts of a circle. 

Source

How to find the circumference of a circle. 

The theory of finding the circumference of a circle is 2π r

π means Pi 

The value of pi is 22/7 (as a fraction)or 3.14.

                                          

Let's find the circumference of a circle which the radius is 7 cm.

so the answer is 44 cm.

Like this you can find the perimeter of any shape. 

Hope you learnt something.

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