Let's do this question, the first question says, find the number of diagonals of a triangle.
Now we know that diagonals are obtained when you join non adjacent purposes right now.
What are the words of this triangle?
You have A, you have B, and you have C, you have three vertices.
Now let's take any vertex.
So let's take Vertex B now you can see that Vertex B in this triangle does not have any known adjacent
vertex.
Right is also an adjacent vertex to Vertex B and C is also an adjacent vertex to Vertex B, therefore
you cannot form any diagonal in the case of a triangle.
Right.
And the answer is zero.
So you do not have diagonals in a triangle.
All right, let's move on.
What are the number of diagonals in a hexagon now?
A hexagon is a six sided polygon.
All right, now, let's take an example.
We have a hexagon over here.
Now, remember, the number of diagonals is given by INSEE to minus in right now.
Over here, you have a hexagon.
So in in this case is six, right?
Because it has six.
What is this?
The answer is six to minus six.
That gives us six in two.
Five by two minus six.
Right.
But what is this?
That 15 minus six, which is equal to nine.
So let's see.
Is that correct?
Over here, let's take this vertex.
Let me join it with its non Anderson.
What is this?
So that's three diagonals that I get here.
Remember, if I join these two, I get a side.
I do not get a diagonal because these two vertices are just what is this?
All right, let's move on.
Let's take this vertex over here and join it to its non Anderson.
What is this?
I get again, three diagonals over here.
Now, let's take this one over here.
I get two more over here because this one is already drawn.
So I don't double counted.
So I get two more over here and over here.
I get one more diagonal.
Is there any more diagonal?
No, right over here.
I have already joined it to this point.
I've joined it to this vertex and I've joined it to this vertex.
Similarly for this vertex, also, I have joined two three other known adjacent.
What is therefore the answer is three plus three plus two plus one.
Right.
Which gives you the answers.
Nine to three plus three plus two plus one.
B over here, three over here to over here and one over here.
That is also equal to nine.
And that's the same answer that we got when we did six to minus six.