Perimeter of regular shapes

Suppose during your holidays, you visit your old storeroom.

You see a lot of discarded things there.

You also found an old clock, a geometry box and a wooden tray.

You noticed that all these things were broken in two pieces.

Since you wanted to fix them up, so you brought few colored tapes to tie them.

You put green tape around the geometry box, red tape around the clock and purple tape around the tray.

When, you put this tape you start at a point and after covering all the sides you see it is a closed figure.

You measured the length of the tape and also the lengths of the boundaries of the figure.

You noticed that the length of tape is equal to the sum of sides of these two dimensional closed figures.

Friends, this distance around any two-dimensional shape is known as perimeter.

The perimeter of any two dimensional figure is given by adding all the sides.

Here, these objects are in square, triangle and rectangle in shape.

Let us try to calculate the perimeter of these shapes.

You may have noticed that these shapes are regular as they do not have any random sides

Let’s try to find the perimeter of regular shapes.

Let’s consider a rectangle .

Now, when we find perimeter of any two dimensional shape we add all the sides of that shape.

So, we can write the perimeter of rectangle as the sum of lengths of all sides as

And, we know the property of rectangle that the opposite sides are equal so we can write perimeter as

Now, after rearranging the sides we get the perimeter as

We can write the perimeter of rectangle in general form as

Now, let’s consider a square and try to find its perimeter.

As all the 4 sides are equal, the perimeter of this square is .

So, we can write the perimeter of square as

Let’s consider a equilateral triangle and try to find its perimeter.

We can find its perimeter as

So, perimeter of equilateral triangle is .

Let’s consider a regular pentagon .

And perimeter of regular pentagon is

Revision

Perimeter of square is

Perimeter of an equilateral triangle is

Perimeter of a regular pentagon is

The End