How to solve cyclic quadrilateral in circle geometry of maths.

JJ ONLINE MATHS CLASS
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7 Video Views·Aug 28, 2026
cyclic quadrilateral simply means a four-sided figure inscribed in a circle. There are some theorems about it that is used to solve this question .
Welcome to my channel. This is a cyclic quadrilateral. Okay, so we are asked to find the angles indicated by the letters.
What does that mean? We are asked to find our m, our n, our k, and our p.
Okay, that sounds so ambiguous, but don't worry.
I'm going to give you the answers step by step in a way that you'll understand. Okay, let's do this.
First of all, we need to know some things about cyclic quadrilaterals. What does cyclic mean?
Quadrature means a quadrature, which is a four-sided figure inscribed within a circle, a cyclic quadrilateral.
First of all, we need to know some circle theorems before we can begin this.
One of the circle theorems states that angles in the same segment are equal.
Angles in the same segment are equal. What does that mean?
If you have a circle like this and you have a chord
This is a chord, which is a line segment that divides a circle into two parts.
But not into two equal parts. It states that when this line cuts the circle
We are going to have two segments. This is the main segment.
the major segment
And this is the minor segment
That is the large one, the major segment. The last one is the minor segment.
Okay, now there's this law that states that any angle, all the angles on the major segment or on any segments
They are equal once they are in the same segment. So what does that mean? It means that
If we have this
It means that as far as I am concerned, I have this
These two angles here. This is a and this is b, notice.
They start at a and end at b, right?
If you have a and you have b, it means that a is equal to b.
Because they are on the same segment on the same segment
That is essentially the same on the main segment as what we have here, something like this.
And we have something like this, any angle we have here will be equal to any angle.
We are going to have them there because two of them are also inside the same segment.
Now let us apply that to what pertains to what we have here.
Now let's use it to evaluate what we have here as you look at this picture.
We're going to see that we have a chord here, right?
Then we have a line drawn from this point; let's call it a and b.
Draw from this a to this b. Okay, and another line drawn from this a to this b, and we have this and this.
So it means that this 60 and this m are in the same segment, so we can say
That m is equal to 60 degrees.
Why?
Angles in the same segment, okay
angles in
the same
segment
Okay, we are able to get the value of our m as what 60
If we have our m to be 60, see this and this, see this end, see this 100.
They are on a straight line. We have something like this day. This is our m
This is our n, and this is 100 degrees. Okay
Now there is another rule that states the sum of angles on a straight line is 180 degrees.
What does that mean? It means that when you add m and n and 100 degrees, you're supposed to get 180 degrees.
Alright, so I've been able to establish the fact that our m is 60 degrees.
so to obtain our n, we can say that
60 degrees, which is our m right
plus
our n
plus
100
What is supposed to give us 180 degrees?
Okay. Now we are going to have 60 plus 100, which is going to give us 160.
So we have 160 plus n equals 180 degrees. That means our n
is equal to 180 minus
160
Let me write it here
So it means that our n is equal to 180 minus 160, which is 20.
degrees
Okay, we have obtained our m and we have obtained our n.
Now, what do we do again?
Okay
There is another law in the cyclic quadratic theorem, and that law states that
The exterior angle of a cyclic quadrilateral
Is equal to the opposite interior angle
Don't worry. I'll explain if this is a circle. I have a quadrature that is something like this.
A square is a four-sided figure. I have an exterior angle. This is what the exterior angle is.
Let's call the exterior angle angle a, this a, okay, and there's another opposite interior angle.
Now this is the interior angle. Let's call the interior angle b, which is opposite to this a.
The law is telling us that this a is equal to this b, that a is equal to b.
I hope you've seen this clearly, because I'm going to clean it now.
Due to the limited space now, let us relate it to this.
This external angle of this cyclic quadrilateral 100 is opposite to this p.
You can see that, so it means that this p is equal to what?
100 degrees, and what is the reason I just gave to you, so we can write
We can write
that p
What is equal to 100 degrees, and what is the reason?
Exterior angle
exterior angle of
A cyclic quadrilateral is equal to the opposite interior angle.
angle
Okay, haven't gotten that yet.
We can obtain our k as usual. How do we obtain our k?
I would like you to do that and give me the answer in the comment section using the segment.
I taught you in the initial sign. Alright, have a lovely day and bye.
