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How to Measure Angles?

  1. Oct 30, 2007 #1
    Hi all,

    This is a weird question,

    I want to measure angles in terms of 360 degrees and not 180. The two lines will share a common point such that Line A ends at the point where Line B begins.

    In order to do this don't you need to define some sort of "standard" so that you can know whether an angle is over or under the 180 mark?

    Anyway, how could I do this?

    (searched google and whatnot but found nothing. Perhaps there's some special keyword to use?)

    Thanks a lot! :)
  2. jcsd
  3. Oct 30, 2007 #2


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    Two lines meeting at a common point define two angles which add up to 360 deg. Pick one.
  4. Oct 30, 2007 #3
    Hi Mathman,

    I don't want to have to pick one or the other. I want the calculation to automatically return the result in the 1-360 degree format, based on some standard I set in the equation.

    Picture two lines at a 90 degree angle. That can either be considered a 90 degree angle or 270 (obviously). But I want to somehow "set" the equation so that when line A is "on one side" of Line B, the angle will be under 180, and if its on the "other side" the angle will be over 180.

    Am I making any sense?

    Thanks again :)
    Last edited: Oct 30, 2007
  5. Oct 30, 2007 #4


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    this is a confusing question!
    _____ |______ Theatha=0 or 360 (after full revolution)

    Like this??

    Notes: Theatha= Angle Value

    What Topic is this??
    What Level? I can only help you A level Downwards...
    hope i donno this kinda helps..

    In terms of 360 what do you mean Theatha/360 ? That doesn return the angle erm.

    If Line A and Line B are opposite to each other won't that mean that its



    Why is this even relevant to you ...

    I'm sorry I just don't understand the question.asked..jus trying to help

    You can always use the Cast Rule to Measure Angles.
    Lets say of Cos(Thetha)=1/2
    _____ |______
    Make Lines from (0,0) obtuse outwards ...on ALL and COS.
    Find Thetha by using calculator Cos^-1 (1/2) = 60 Degrees.
    then measure First is ..60 and the second is 360-60 = 300 Degrees.
    Hence Thetha =60,300 . ect ..

    You can measure angles using Thetha = +/-PV +360n but i donno what level you're doing..
    its perplexing ..just cant understand it.
    Last edited: Oct 30, 2007
  6. Oct 30, 2007 #5
    Hi Phy, Thanks for following up.

    Let me illustrate my point clearer by using a simple pictured In the Attachment below.

    As you can see I have a blue and orange area, and two lines, A and B. I want to define the equation such that I will 'pick' an arbitrary 'side' of line A, such that when line B falls on one side it will be less than 180 degrees and on the other greater than 180.

    Attached Files:

  7. Oct 31, 2007 #6


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    Looking at the diagram, it looks like you should place the A,B common point at the origin of a standard cartesian coordinate system and make A lie along the y axis in the positive direction. Then if the x component of B is positive the angle is less than 180 deg., if negative the angle will be greater than 180 deg.
  8. Oct 31, 2007 #7
    Hey mathman, thanks, I see where that is going and think I can make something work :D
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