1
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Let's do this question, a bizarre tangent to the circle.

2
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Is a second that is extended to be all right.

3
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So this is a straight line.

4
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Angle C is 30 degrees angle ACB is 70 degrees.

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The question is find angle C or D.

6
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All right.

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So we have this angle as 30 degrees and this angle as 70 degrees.

8
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Now, pause the video, give it a try and then let's do it together.

9
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All right.

10
00:00:28,970 --> 00:00:33,380
Let's do it together now, because this angle over here is 30 degrees.

11
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Therefore, Angle AC DC also will be 30 degrees.

12
00:00:37,640 --> 00:00:37,990
Right.

13
00:00:38,150 --> 00:00:39,950
I suppose he can dungen theorem.

14
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Right, because this is the angle formed by the tangent and AC, which is the second.

15
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Therefore this angle over here, which is also subtenant by AC, will be equal to this angle over here.

16
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Right.

17
00:00:51,440 --> 00:00:53,930
So AC is equal to 30 degrees already.

18
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Now what about angle A, C, D?

19
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Because this is a straight line, right.

20
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Therefore this angle and this angle together form 180 degrees.

21
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Right.

22
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Therefore, Angle A.D. is 180 minus 17.

23
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That's equal to 110 degrees.

24
00:01:09,710 --> 00:01:15,660
All right, let's model over here and we can have a C a D, right.

25
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What would be this angle?

26
00:01:17,190 --> 00:01:19,460
You know, that A.D. forming a triangle.

27
00:01:19,700 --> 00:01:23,870
So angle C 80 will be 180, minus hundred and ten.

28
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Minus 30.

29
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Right.

30
00:01:26,160 --> 00:01:30,870
But that is equal to 40 degrees, so you have this angle over here as 40 degrees.

31
00:01:31,050 --> 00:01:35,900
Now we need to find angle codi angle see or you can see that angle.

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What is the measure of ArchCity right now?

33
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That would be double the measure of the angle SUB-STANDARD by this arc.

34
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Now angle see, it is supported by side and we have found that the measure of that is 40 degrees.

35
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Therefore Anglesey already will be two times 40, which is equal to 80 degrees.