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  • Math help needed for layout. Please.

    Please dont think of me as stupid or lazy, Ive been trying to get this on my own for a couple days now and I'm stumped. The school I went to did not allow me to take mathamatics after the 8th grade, long story but true. They said I had enough ? Made me take a study hall instead despite my opposition.
    Any way I need to find the exact angles of a right triangle. I can get close enough with a protracter for a couple uses but I'm useing this angle repeatedly and the small error is showing up big time as I progress with my layout.

    Heres the dimentions :
    Side 1 ) 1.875
    Side 2 ) 3.375
    Hypotenuse ) 3.8608

    Obviously one is 90 and I get 61 and 29 for the other two but that dosnt seem close enough after repeated use of it. I hope its just a simple formula that I cant find or figure out. If one of you can help me it would be greatly appreciated. Thanks.
    To all who contribute to this board.
    My sincere thanks , Pete.

    Pureox OA
    Westinghouse 300 amp AC stick
    Miller Syncrowave 250
    Hexacon 250 watt solder iron

  • #2
    Burn,

    I'm not to good at math either, but if I remember I'll ask my son when I get home tonight. I alway's joke around with him asking if he want's help doing his home work, thank God he always say's no thanks dad Iv'e got it covered. He's in 10th grade and doing 12th grade math and setting the curve for the class.

    Pete

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    • #3
      No Problem. Here you go:

      Because this is a right triangle, you can use trig (Sine, Cosine, Tangent). The easiest way, IMO (there are a few), is to use Tangent since you know the two sides accurately (the hyp will be rounded).

      Tangent(angle) = (Opposite Side)/(Adjacent Side)

      So: Tangent (angle) = 1.875/3.375 = 0.5555

      Angle = Inverse Tangent (0.5555) = 29.0546 degrees

      The other angle is: Inverse Tangent (3.375/1.875) = 60.9454

      The other way to find the last angle is: 180 - 90 - 29.0546 = 60.9454

      I hope this helps, and is not too confusing. You will need a scientific calculator to figure this out. Normally Inverse Tangent is evaluationed by a 2nd Function button then press Tan.

      If you still have questions, I will be happy to try to explain this better, but it will have to be this evening at the earliest.

      Joshua

      EDIT: BTW, if you have a Machinery's Handbook, it is in there under Tangent also. Page 88 of the 27th Edition.

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      • #4
        math = 29.05* and 60.95*, your protractor is on the money. Are you sure you got everything else correct?
        hre

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        • #5
          The resultant angles are 29.0551 and 60.9470. I use the sine of the angle = the opposite leg divided by the hypotenuse. In the case of the first angle ( I called it "a") sin (a) = 1.875/3.8608. Then, taking the arcsine of 1.875/3.8608 (commonly labeled "asin") results in the desired angle.

          A quick and dirty way to remember which sides will yield the sine, cosine and tangent of a desired angle is (not don't laugh) Cheif SohCahToa. Sin (a) = opposite leg/hypotenuse. Cos (b) = adjacent leg/ hypotenuse. Tangent (c) = opposite leg/ adjacent leg. The resultant angle will be determined useing the appropriate asin, acos or atan as I did above.

          Hope this helps.
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          • #6
            Thanks a lot guys. That doesnt seem to be enough to make a differance. When I line up individual parts of the layout every thing fits , so I'm pretty sure my proceedure is right. When I start puting the parts together to compleete the layout it gets progrssively more out of wack. I might just have to double check the positioning of every thing.
            Thank you again, at least now I know where I stand on the angles.
            To all who contribute to this board.
            My sincere thanks , Pete.

            Pureox OA
            Westinghouse 300 amp AC stick
            Miller Syncrowave 250
            Hexacon 250 watt solder iron

            Comment


            • #7
              The error accumulation can be a killer. How many parts do you have to put together?. Is this going to be a dome or something like that?
              SolidWorks Premium
              SolidWorks Simulation Pro
              MM210 w/3035
              TA185TSW
              DG Piranha II
              Sharpie Deluxe
              Stars & Stripes BWE
              Blue Optrel Satellite

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              • #8
                Good news. I multiplied the amount I was off, .05 , by the number of times I used it and came out to the amount I'm off by.
                The bad news is I have to start over now. Also thanks for takeing the extra effort to explain it to me. I'm going to do a few problems and see if I got it and write this info down as I use angles a lot.
                To all who contribute to this board.
                My sincere thanks , Pete.

                Pureox OA
                Westinghouse 300 amp AC stick
                Miller Syncrowave 250
                Hexacon 250 watt solder iron

                Comment


                • #9
                  Originally posted by katiebo
                  The error accumulation can be a killer. How many parts do you have to put together?. Is this going to be a dome or something like that?
                  Its a rectangular headlight bucket with 7/8" radious corners and a sloped top. There is a lot of angling involved and I dont mean fishing. Once I get the layout done I plan to take pictures of the progress and post it hear. All my latest threads relate to this project. You might have seen the one where I made the radius attachment for the brake. The post with the antique equipment was a result of working on this project.
                  To all who contribute to this board.
                  My sincere thanks , Pete.

                  Pureox OA
                  Westinghouse 300 amp AC stick
                  Miller Syncrowave 250
                  Hexacon 250 watt solder iron

                  Comment


                  • #10
                    I can follow this to the point of tangent angle = oposite side / by adjacent side and get .5555, then I'm smoked. I'm going to have to get my buddys daughter to teach this to me. Thanks for the effort.
                    To all who contribute to this board.
                    My sincere thanks , Pete.

                    Pureox OA
                    Westinghouse 300 amp AC stick
                    Miller Syncrowave 250
                    Hexacon 250 watt solder iron

                    Comment


                    • #11
                      Are you using a scientific calculator?
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                      • #12
                        A lot of people have a scientific calculator and don't even know it. Open the Windows calculator (Start|Programs|Accessories|Calculator) and choose View|Scientific from the menu bar (click the Inv check box to get the inverse functions). Voila, you've got the trig functions you need. For free, sorta.

                        Here's a quick and dirty web triangle calculator:
                        http://www.machinist-calculator.com/...angle-Eng.html

                        If you google 'basic trigonometry' there are lots of really good sites that will step you through the theory using graphics which makes it much easier to follow than text. Hope this helps.

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                        • #13
                          katiebo :
                          No I wasnt useing a scientific calculater.

                          drscotch :
                          No , I didn't know it was there and yes it is there. I'll have to give this another shot.
                          To all who contribute to this board.
                          My sincere thanks , Pete.

                          Pureox OA
                          Westinghouse 300 amp AC stick
                          Miller Syncrowave 250
                          Hexacon 250 watt solder iron

                          Comment


                          • #14
                            OK !!!!
                            I got it now.
                            I think I'll still have my buddys daughter teach me more about the theory but this is enough to get me started. I'll tell you what, no math past the 8th grade hurts. When I was doing sign work I came up with a way of figureing angles compleetly differant than the correct way, but it worked. Once I learned from my brother the right way to figure angles it got a lot easyer. I was starting with a flat peice of sheet metal and calling it 0 degrees when I should have been calling it 180. The meathod I developed worked but it was not near as easy to use as the right way.
                            I hate to keep repeating myself but thanks again.
                            To all who contribute to this board.
                            My sincere thanks , Pete.

                            Pureox OA
                            Westinghouse 300 amp AC stick
                            Miller Syncrowave 250
                            Hexacon 250 watt solder iron

                            Comment


                            • #15
                              here are 2 great books on the type of math we (pipefitters at least) use all the time, very easy to understand and not too expensive.

                              http://www.pipefitter.com/mtbo.html
                              http://www.pipefitter.com/pfmg.html

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