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Math Help - Polar Graphing

  1. #1
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    Polar Graphing

    Hi all,

    I've posted a few questions tonight, last one I promise.

    I'm trying to graph polar coordinates and understand how to do it with r = blah blah, and that gives your distance at the set angle.

    I've been given the equation \theta^2 - 1 = 0 to graph however, and I've got no idea to be honest. Obviously I could rearrange to make theta the subject (equals +/- square root of 1) but still don't see how that fits onto the circular graph.

    How do I find the values of r?

    Cheers.
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  2. #2
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    Quote Originally Posted by Peleus View Post
    Hi all,

    I've posted a few questions tonight, last one I promise.

    I'm trying to graph polar coordinates and understand how to do it with r = blah blah, and that gives your distance at the set angle.

    I've been given the equation \theta^2 - 1 = 0 to graph however, and I've got no idea to be honest. Obviously I could rearrange to make theta the subject (equals +/- square root of 1) but still don't see how that fits onto the circular graph.

    How do I find the values of r?

    Cheers.
    If I gave you the equation x = 1 to plot, how would you plot it, after all, I didn't give you any y values!

    You'd plot a vertical straight line that crosses the x axis at 1 and continues through negative infinity to infinity in the y direction!

    So you have to do the same here. When you plot an equation, you are plotting ALL possibly values that satisfy that equation. In this case, there are an infinite number of values of r that satisfy that equation. So basically, your polar graph is a straight line the has an infinite r, and makes an angle if  \pm 1 with the x axis!
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  3. #3
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    Yeah I think I'm dumb and overcomplicating things, trying to plot it on a circular graph because it's when I associate with polar, when a typical graph is what I needed.

    Thanks.
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  4. #4
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    Quote Originally Posted by Peleus View Post
    Yeah I think I'm dumb and overcomplicating things, trying to plot it on a circular graph because it's when I associate with polar, when a typical graph is what I needed.

    Thanks.
    Well you should be plotting it on a polar graph! But the shape of the curve in that graph isn't necessarily 'curved' or 'circular'.

    You can have a straight line graph on a polar coordinate system, and this is what we have here.

    I've attached a Matlab plot of what you should be seeing.

    The lines continue on to infinity in the direction they are heading.
    Attached Thumbnails Attached Thumbnails Polar Graphing-untitled.jpg  
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