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Re: Perpendicular lines do not appear perpendicular


Hi Bill,

It looks perfectly perpendicular on my screen. Could you check the
resolution to which your monitor is set? It might be that you have set
it to a non native resolution with an aspect-ratio that's not 16:10
(which would be natural for your screen).

Cheers -- Sjoerd


On May 31, 12:35 pm, Bill <WDWNORW... at aol.com> wrote:
> Perpendicular lines do not appear perpendicular
>
> Hi:
>
> I have taken the line equation 2*x+4*y-6==0, and rotated it 90 degree=
s counterclockwise about {0,0},
> using a 3x3 rotation matrix.
> Here's the Mathematica 6.0.1 code that I used:
>
> rMat = {{Cos[90 Degree], - Sin[90 Degree], 0}, {Sin[90 Degree],
> Cos[90 Degree], 0}, {0, 0, 1}}
>
> l={2, 4, -6}
>
> rMat.l
>
> Output: {-4,2,-6}
>
> Placing these numbers into the general form of the equation of the line A=
x+By+c=0, I get -4*x + 2*y - 6 == 0.
> Placing the 2 perpendicular line equations into ContourPlot:
>
> ContourPlot[{2*x + 4*y - 6 == 0, -4*x + 2*y - 6 == 0}, {x, -4,
>   4}, {y, -4, 4}, AspectRatio -> 1]
>
> and plotting, I notice that on my pc screen that the lines do not look pe=
rpendicular, as does the plot frame.
> Perhaps this is just my computer screen, a HP f2105. I can hold up a squa=
re cut piece of paper to the lines
> on the screen, and notice the out-of-square condition. I used AspectRatio=
->1, but still no joy.
>
> Question: Can someone suggest a remedy for my problem, if one exists?
>
> Thanks in advance,
>
> Bill
>
> PS. Mathematica 6.0.1 on a pc with Win XP.



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