Class 4    Math    Calculate Perimeter

Identify perimeter of an asymmetrical shape

Question: In the below diagram can you find out what is the length of its boundary. It is given that its width and height have same dimension that is 1 cm ?

     calculate perimeter of a shape

Answer: To calculate boundary, we only need to consider the highlighted dark border of the given diagram. We need to add each side to calculate the entire boundary of the diagram. Let us consider the left boundary only as shown in the below diagram:

learn perimeter logic

In order to keep it visible we have highlighted it with the red color. Now its given that each side has a length of 1 cm. By looking at the diagram we know that there 5 sides on the left of this diagram. We are multiplying 1 cm with 5 to get the left boundary. Which is: 1cm x 5 = 5 cm. We know that length of left boundary is 5 cm.

Let us now take top of the diagram, as shown in the below image:

area and perimeter concept

While calculating top boundary, we see that there are eight sections that we need to cover (refer highlighted section). In order to calculate the top border of this diagram, we need to multiply 1 cm with 8. Which is: 1cm x 8 = 8 cm.

Now let us calculate the right boundary, please refer the below diagram to understand the right side boundary and hoe many sections we need to cover:

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This is pretty simple, we need to multiply 1 cm with 3 to get right hand side border, which is 3 cm.

Finally calculate border of the bottom portion of the diagram. Understand the bottom by this diagram:

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For the bottom boundary we need to multiply 1cm with 6 as there are 6 sider. So bottom boundary is 6 cm long.

Finally we will add all the borders to get the border of this shape which will be: 5 cm + 8 cm + 3 cm + 6 cm = 22 cm