PERIMETER AND AREA FOR CLASS 4TH AND 5TH (L-1) BY SASMITA MISS

Añadido: 2026-05-31

[00:00:00]Good morning to all dear students. My name is Amita Sahu math teacher. Okay. So today we'll discuss about a chapter that is common to both for your standard four and standard five. Chapter name is perimeter area. Okay. This is a very interesting chapter. Okay. So in this lecture we will cover we'll try to cover the perimeter. Okay.

[00:00:32]So before going to the topic I to tell you a story a very interesting story. So please listen carefully. Okay.

[00:01:03]Okay.

[00:01:07]Two students Okay. Two students suppose suppose this is a girl. This is a boy.

[00:01:28]Okay. This her name is Swati and his name is suppose O. Okay.

[00:01:41]Sorry.

[00:02:02]Name is O.

[00:02:05]They both are brother and sister. Okay.

[00:02:09]They also have a beautiful garden. Okay.

[00:02:16]So, Flowering plants.

[00:02:46]Okay. There is a cow who always come to their garden and destroy their plants.

[00:03:05]Naughty.

[00:03:24]Fencing.

[00:03:39]Okay.

[00:03:51]X keeperencing.

[00:04:27]Okay.

[00:04:40]Okay.

[00:04:52]Just a minute.

[00:05:08]garden.

[00:05:15]Okay.

[00:05:29]Okay.

[00:05:33]Second side.

[00:05:36]Then 20. Then 10 m.

[00:06:20]Okay. So, total of all the four sides.

[00:06:23]Okay. So, First side is 20 m. Then the second side is 10 m. The third side is 20 m. And the fourth one is 10 m. Okay.

[00:06:40]So see 20 m + 10 m + 20 m + 10 m. So you can find out 10 m 20 + 10 = to 30. 30 + 20 = to 50. 50 + 10 = 60 m.

[00:06:59]Okay.

[00:07:01]So this 60 m is the sum of all sides.

[00:07:07]Okay. And this 60 m is called the perimeter of these guardian. Okay.

[00:07:16]So here perimeter is the sum total of all the sides. So what is perimeter?

[00:07:27]Perimeter perimeter of any closed shape is the total distance around its edges. Okay.

[00:07:53]perimeter of any closed shape is the sum of all its sides. Okay.

[00:08:03]So to calculate perimeter of any clos we can add all its sides.

[00:08:11]So now you can calculate the perimeter of any clos.

[00:08:17]So let's find out this is a problem you know suppose this side is 10 m 10 cm and this side is suppose 5 cm and this side is 10 cm.

[00:08:45]Okay. So what is the perimeter of this triangle? Now perimeter perimeter is the sum of all sides. So perimeter of this triangle here the perimeter is equals to s.

[00:09:04]So 10 m 10 cm + 5 cm + 10 cm find out 10 + 10 + 5 25 cm. So this 25 cm is theime.

[00:09:27]Okay.

[00:09:29]Now find out the perimeter of this.

[00:09:32]Suppose this side is 2 cm. This side is 5 cm.

[00:09:41]This side is 10 cm. This side is 10 cm.

[00:09:47]And this side is 5 cm.

[00:09:51]Now we can calculate it.

[00:09:58]perimeter is equals to sum of all times. Start from this this side here 2 cm.

[00:10:09]This side is 5 cm.

[00:10:13]This side is 10 cm.

[00:10:20]This side is 5 cm. And the last one is 10 cm.

[00:10:27]This is a pent you know pentagon 5.

[00:10:32]Okay. So we can calculate it perimeter by adding all five. So now 2 cm + 5 cm + 10 cm + 5 cm + 10 cm 10 + 10 20 then 5 + 5 10 20 + 10 = to 30 30 + 2 = to 32 cm. Okay?

[00:11:02]Now perimeter. Suppose this side is 2 cm.

[00:11:08]This side is 2 cm.

[00:11:12]This side is suppose 5 cm.

[00:11:16]This side is 7 cm.

[00:11:21]This side is 10 cm. This side is 8 cm. Okay. This is a L figure. You can calculate it perimeter by adding all its sides. Okay.

[00:11:37]Then calculate it.

[00:11:45]Perimeter equals to sum of all sides.

[00:11:48]Start from this side and go along it.

[00:11:52]Okay. First one is 2 cm.

[00:11:55]Then the second one is 5 cm.

[00:11:59]Third one is 8 cm. Fourth one is 2 cm then 10 cm then 7 cm m.

[00:12:13]So calculate calculate this perimeter.

[00:12:45]34 20 m. Okay.

[00:13:05]Then we'll discuss about the perimeter of a square. This is a square. Okay.

[00:13:18]And you know that all sides of a square are equal in length. Okay. Suppose if this side is 10 cm, this side is also 10 cm. This side is also 10 cm.

[00:13:36]This side is also 10 cm.

[00:13:40]Next we can easily calculate okay by adding all its sides.

[00:13:50]So perimeter is equals to 10 cm + 10 cm + 10 cm + 10 cm.

[00:14:10]See here 10 is four times. See 10 10.

[00:14:18]Okay. So we know that multiplication is repetative and here 10 is added four times. So we can write it like 4 into 10 cm.

[00:14:32]Okay. So this is equals to 40 cm.

[00:14:40]Okay. Now I'm giving another example.

[00:14:56]Okay. Suppose this side is 5 cm. This side is 5 cm. This side is 5 cm. And this side is 5 cm.

[00:15:06]Now perimeter is equals to 5 cm + 5 cm + 5 cm + 5 cm.

[00:15:31]So see here five is four times. So you can write it like 4 into 5 cm.

[00:15:43]So 4 20 cm.

[00:15:48]Okay. See.

[00:15:52]So focus on this line. See here four is multiplied with 10 cm. And what is 10 cm? And 10 cm is the length of this square side length of this square. And here four is 5 cm 5 cm in this is the side length of this square. So we can draw a conclusion from these two examples like perimeter of a² is equ= to 4 into here four is 10 cm 10 cm is length of this side. Your 4 is 5 cm. 5 cm is the length of this side. So we can draw a conclusion that perimeter of a square is equals to 4 into s. Okay.

[00:17:04]Also if perimeter is given suppose perimeter Suppose perimeter of a square is given this is 36 cm. Okay.

[00:17:36]36 cm. So we can calculate it.

[00:17:52]Now side is equals to side of it square is equals to perimeter divided by 4.

[00:18:13]perimeter divided by 4. Okay.

[00:18:22]So see here perimeter = to 36.

[00:18:32]Here perimeter is equals to 36 cm divided by 4. So 4 36 9 4 9 36.

[00:18:58]So it side is 9 cm. Okay. If side is given you can calculate it perimeter and if perimeter is given also you can calculate it side. Hope it is clear.

[00:19:16]Okay.

[00:19:23]Now we will discuss about the perimeter of a rectangle.

[00:19:34]Okay, this is a rectangle and the opposite sides of the rectangle are equal in length. You know that this side is length, this side is bread. Opposite sides are equal. So this is also length and this is bread. If length is equals to suppose 30 m. Okay. And bread is equals to 20 m.

[00:20:09]We know that opposite sides are equal in length. So if this side is 30 m, this side is also 30 m. If this side is 20 m, this side is also 20 m. Okay.

[00:20:25]Now we can calculate it by adding all