1
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Now, using the concept of tangents, we are going to draw an oval, okay?

2
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In this exercise, they give us the main axis.

3
00:00:10,199 --> 00:00:12,400
This is the main axis, okay?

4
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And it's already divided in three, okay?

5
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Here we have the axis, okay?

6
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The oval must be enclosed here.

7
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and these two points that the exercise gives us

8
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are going to be the center of the first arch

9
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and the center of the second arch, okay?

10
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So we are going to draw a circumference, okay,

11
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with the needle of the compass in this point

12
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and the radius, the distance on both, yeah?

13
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So when we draw the circumference, okay,

14
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it has to arrive to the end of the axis, yeah?

15
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And here we are going to do the same, okay?

16
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With the same radius.

17
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We are going to draw another circumference.

18
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Okay?

19
00:01:14,920 --> 00:01:19,180
So, where the two circumferences cut each other,

20
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we are going to have the third center of the circumference

21
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and the fourth center, okay?

22
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And now the problem, the question is

23
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how long must be the radius of this third and fourth circumference, okay?

24
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So, we are going to use the concept of tangents.

25
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I remind you that two circumferences will be tangents,

26
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will be touching each other just in one point

27
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when the centers are aligned, okay, in the same line with the point of tangent.

28
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So, if we have here the first circumference

29
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and this is the center of the fourth circumference,

30
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we are going to make a line that joins one center with the other and enlarge it till the circumference, okay?

31
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So here we will have a point of tangent, okay?

32
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I'm going to call it 0.4, okay?

33
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The same with the second circumference, okay?

34
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I'm going to call it 0.3, okay?

35
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So, once we have calculated the point of tangents, I can draw the circumference, placing the compass in the center and taking the pencil to the points 3 and 4, like this.

36
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Do you understand?

37
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Now, I'm going to do the same with the third center.

38
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Okay, just join the centers, okay, make lines that join the centers with the edge of the circumference, so to speak the edge, okay, and here the same, okay, it's just crossing through the centers, and here we will have the point two, for example, and here we'll have the point one, okay, and now we do the same.

39
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okay center in 0.3 okay and making this arch till point one two two okay now i'm going to mark sorry

40
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because of the focus i'm going to mark the oval with the pen but this is something that you

41
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haven't got to do okay don't do it just mark it a little bit more with a pencil okay what do we have

42
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to mark okay you have to do it with the pencil okay i will do it with the pen we have to mark

43
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in circumference one only the points that goes uh from the fourth point the the arch that goes

44
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from the point fourth to the point two okay so like this mark only this part of the oval okay

45
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only this part in the second circumference the same from point three to point one okay like this

46
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okay i do it with a pen not with a pencil now in the fourth circumference

47
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we are going to join these points yeah okay and in the third circumference the same

48
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Okay, so I have my oval using the concept of tangent.