In this video, let's discuss what we mean with polygons.
All right, let's take an example of a polygon.
This is a five sided polygon, which we call the Pentagon.
Now, let's try to understand what we mean with polygons.
And let's also try to visualize the definition using this example over here.
All right.
The polygon is a simple closed figure.
All right.
What does that mean?
It's simple.
That means it does not cross itself.
For example, if you have a shape like this, this is not a polygon because you can see over here that
it crosses itself at this point.
Right.
So polygons do not cross themselves.
And it is a closed figure.
That means it's not open.
But this over here is an example of an open shape.
Right.
The polygons have to be closed.
Also, polygons have to be made up of entirely line segments.
So if you have a shape like this.
This is not a polygon, right, but whenever you have the word polygon in a question, you can be sure
that the whole shape is made up of nine segments.
All right, let's move on.
Let's try to get familiar with some common polygons.
So we have seen that polygons are made up of entirely line segments.
But let's see if a polygon has five nine segments.
That's what we call a Pentagon.
All right, now, if it has four line segments, that's what we call a quadrilateral.
All right, and if it has three lines, we get a triangle.
And what do you think can be made with just two lines?
No, you cannot form a polygon with two lines.
You need a minimum of three line segments to form a polygon.
All right.
Now let's move on.
Let's see how to name a polygon.
Let's take an example.
We have this Pentagon over here.
Let's name these.
What is this as abcde e.
So that's A, B, C, D, E, all right, now I can call this polygon as polygon, a, b, c, d, e,
you can see that the corners are taken in order.
So I can call this as A, B, C, D, E, or I could even call it s e e, b, c, b right.
Now, what is a way in which it cannot be named.
You cannot call it as a c e right.
That's E over here and then you have C you cannot go from E to see when you're naming it.
It has to be taken in order.
You could start from any point.
So you can also call this as an e e, b, C, that is fine because you're going in this, this dictionary,
but you have to take the vertices in a particular order.