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Modding The angles of a pyramid

Discussion in 'Modding' started by Simplegreen21, 10 Dec 2003.

  1. Simplegreen21

    Simplegreen21 What's a Dremel?

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    I need to find some angles for a pyramid. The angle I am speaking of is the angle made by the adjacent sides of the pyramid. I first thought this angle would be 90 degrees because the base of the pyramid is a square, but after trying to test that I don't believe it is. I need a way to find this angle other than measuring with a protractor. I assume the angle is based on the base and height measurements and therfore varies for different sized pyramids. Perhaps I am missing the obvious, but I can't for the life of me figure this one out, any help would be greatly appreciated.

    Thanks for your time,
    Simplegreen
     
    Simplegreen21, 10 Dec 2003
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  2. RR5

    RR5 What's a Dremel?

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    I think the solution is four isosceles triangles. Where only two of the sides are the same length.
     
    RR5, 10 Dec 2003
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  3. Sid

    Sid Banned

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    Sid, 10 Dec 2003
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  4. eddie_dane

    eddie_dane Used to mod pc's now I mod houses

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    eddie_dane, 10 Dec 2003
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  5. cpemma

    cpemma Ecky thump

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    The angle between sides taken parallel to the base is 90° but the angle taken at right-angles to 1 face isn't & depends on the height.

    Just do a sketch & use sine and cosine formulae, the link is for a 3-sided base but could be modded. ;)
     
    cpemma, 10 Dec 2003
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  6. Simplegreen21

    Simplegreen21 What's a Dremel?

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    Thanks guys, I have been to that site before, but didn't look into it very much, I feel somewhat foolish. Well, time to get calculating. It is time to eat my words and apologize to my former highschool math teacher, I will use this stuff some day. ;) Hope i still remember how to do it all.

    Thanks again,
    Simplegreen
     
    Simplegreen21, 10 Dec 2003
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  7. Simplegreen21

    Simplegreen21 What's a Dremel?

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    Well, I think I have it! the total angle is 103.47705 degrees. If any of you would like to check my work. The triangles I am working with have a height of 14.5 inches and a base of 14 inches. Thanks for the help.

    Yours truely,
    Simplegreen
     
    Simplegreen21, 10 Dec 2003
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  8. RR5

    RR5 What's a Dremel?

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    I would, but I suck at math period.

    Hang on, I need to use high school PE to install a network interface card into a pentium 4 computer so it can join the lan party.
     
    RR5, 10 Dec 2003
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  9. woz_mann

    woz_mann What's a Dremel?

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    the angles on a pyramid are not fixed

    they will vary depending on your height and base size etc. If I can find my TI-83 I'll do the math for your exact measurements
     
    woz_mann, 11 Dec 2003
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  10. Kalym

    Kalym What's a Dremel?

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    The only thing I remember from High School maths.

    Basic Triganometry (kant spell)

    SohCahToa

    Sin theta = Opposite/ Hypotininuse

    Cos theta = Adjacent / Hypotinuse

    Tan theta = Opposite / Adjacent

    Then it's just a matter of re-arranging the equation.
     
    Kalym, 11 Dec 2003
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  11. linear

    linear Minimodder

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    linear, 11 Dec 2003
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  12. Simplegreen21

    Simplegreen21 What's a Dremel?

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    Thats a nice program Linear. I have only one problem, none of the angles listed are greater than 90 degrees, and I know that the angle made by the two faces is greater than 90. Also, I am quite sure that the pyramid in the Toronto math site is a four sided pyramid as he makes reference to the base being a square. I am somewhat confused now, as I thought I had the answer I needed, perhaps I am reading your program wrong, some of angle decriptions are not in my vocabulary ;)

    I think I may have found the problem. Your program seems to take the angle parallel to the base, by doing this, the angle the two faces make will always be 90 degrees for any four sided pyramid. The angle needs to be calculated perpendicular to the slant of the side. I think the toronto math department may have gotten it ( though I do not understand how they got it, I'll have to look into it).

    Thanks,
    Simplegreen
     
    Simplegreen21, 11 Dec 2003
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  13. linear

    linear Minimodder

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    All I did was turn this into an excel spreadsheet.

    It's not giving you the miter angles, it's just the dihedral angles between faces. I was gonna add a section to figure the miter angles, but the dihedral angle between faces (phi) is so close to 90°for all cases, I figure it's not worth splitting hairs over the decimal places. Set your saw for 45° for that, and it's up to you how you want to set up the base-to-face miter, but I know I'd skip mitering the base and miter the bottom edge of the faces to beta.

    Try entering a range of different values for h, it never gets more than a degree off 90° for any useful heights.

    See also (http://www.ex.ac.uk/trol/scol/calpyr.htm) my numbers agree with his, but he doesn't show a face-to-face angle.
     
    linear, 12 Dec 2003
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