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Regular pentagon inscribed in a circumference - Contenido educativo
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Now we are going to draw a regular pentagon inscribed in a circumference,
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and this is the most difficult exercise regarding polygons, okay?
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So please pay attention, stop the video all the times you need it,
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and make me questions in class if you have doubts, okay?
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The first thing we are going to do is to draw a diameter, as we usually do, okay?
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Okay, and now we are going to draw another one perpendicular to the previous one.
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Okay, so I place here the square and down below I put the cartabon and I turn the square.
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Okay, and I slide it till the center of the circumference.
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Okay, I have two perpendicular diameters.
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Yeah, I'm going to put names to the points so we can understand each other.
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The center of the circumference is going to be O and this is going to be A.
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And also it's going to be the first vertex of my pentagon.
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OK, this is going to be B. It's not going to be part of my pentagon.
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This is going to be C and this is going to be D.
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OK, C and D are not parts of my of my pentagon either.
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okay now I'm going to find the middle point of the radius OD okay so what I
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have to do is to we are going to draw kind of a sector line okay so I'm going
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to place the compass in D okay and with the same radius just the radius OD
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I'm going to make an arch that cuts the circumference okay so then I'm going to
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join these two points okay where the art cuts the circumference okay those points
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are not important for anything well just for this for the sector line that we are
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drawing but this point is not part of the circumference not neither this one
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okay and here we have the middle point M okay the distance OM is supposed to be
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the same that OD, okay? Let's check it. Let's check it with the compass, okay? DM, oops,
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here, DM, okay? It must be the same, okay? Okay, MO. This exercise, as I have said, is
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the most difficult because there are a lot of steps, okay? If you make mistakes in one
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mistake you will have more mistakes over and over okay so now what we are going
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to do is to place the middle of the compass in M and using the radius MA
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okay the pencil in A we are going to make another arch okay cutting this part
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of the diameter okay this radius and this point is going to be called N okay
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n is not in the middle of this radius anymore okay here there is a golden
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proportion okay or golden ratio but this we will talk about that in further years
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okay and the most important thing that you need to know is that a n okay a n is
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the misser of the side of the pentagon, okay? AN is the side of the pentagon, okay?
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The polygon of five sides. So what we are going to do is to take this misser, that's
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why it's important to have a very good compass, okay? And placing the needle in A,
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we are going to make an arch okay that cuts this circumference four times okay
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first time second time okay this is going to be number two and this is going
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to be number five okay the vertex of my pentagon now I'm going to place the
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compass in two okay making the point number three three okay and I'm going to
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place my compass in five okay always is the same measure okay a and yeah do you
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see the same measure and we put it here okay this is point four and just check
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it okay the same measure must be here okay between four and three oh yeah must be the same measure
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okay the distance between the five points is the same we have divided the circumference in five
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equal parts now we are going to draw joining in each point each point each vertex we will have
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our regular pentagon that is so so beautiful and so so perfect
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- Idioma/s:
- Autor/es:
- Lucía S.
- Subido por:
- Lucia S.
- Licencia:
- Reconocimiento - Compartir igual
- Visualizaciones:
- 152
- Fecha:
- 28 de septiembre de 2021 - 19:06
- Visibilidad:
- Público
- Centro:
- IES AVENIDA DE LOS TOREROS
- Duración:
- 05′ 29″
- Relación de aspecto:
- 1.42:1
- Resolución:
- 640x452 píxeles
- Tamaño:
- 123.18 MBytes
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