In this video, let's discuss about the circumference of a circle and the area of a circle.
All right.
We have seen that the circumference of a circle is the same thing as the perimeter of a polygon, right?
It's the distance around a circular region.
So the circumference is the distance around the circular region or it's the measure of the border.
Right over here you have a circle.
Now, the circumference would be this distance.
Right, so this distance is the circumference now let this be the center of this circle.
Now, if you draw a line through the center, we get a diameter, right?
All right.
Let's keep that over here.
Now, let me call the circumference as see, OK?
Now, if you take any circle and if you divide see with their diameter, if you divide the circumference
of this circle with the diameter of the circle, you will get a unique ratio.
It will be a constant or any circle.
And that constant is what we have defined us by.
Now, the value of PI is approximately taken as twenty two by seven or three point one four.
Now in actual case, by is an irrational number.
So it's it's an unending number.
The decimals will never and it will keep on going like that.
But in problems we approximate it to twenty two by seven or three point one for now using this part
C by two R gives you pi.
Right.
What is the radius.
Twice the rate is that the diameter now C by two R is equal to PI.
Therefore using this concept we can find that the circumference of a circle is equal to two pi are all
right now, having established how to find the circumference of a circle.
Let's move on and find how to find the area of a circle.
Over here I have a circle and let's see by the center of the circle and R is the radius of this circle.
Now if you want to find the area of the circle that is this region over here, then all you need to
do is you need to multiply by with the square of the radius.
So the area of a circle is given by a single payer square.
So if you are given that the radius is equal to seven centimeter and you want to find the area of this
circle, what you need to do, you can approximate PI to twenty two by seven and radius square will
be seven to seven.
And that gives you the answer as 22 into seven centimeter square.