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How to draw neat spiral?

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Terry Pinnell

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Jun 26, 2003, 5:23:12 AM6/26/03
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I need to draw a spiral, starting say 0.5" from the centre point and
finishing after 3 'spirally circles' about 2" (5 cm) away, i.e 4"
diameter at maximum. Suitable for placing in a Word document with
further annotation and titling.

I made a half-hearted attempt with the Excel formula
r = 1 + a/360

i.e.
a r
5 1.013888889
10 1.027777778
15 1.041666667
20 1.055555556
25 1.069444444
30 1.083333333
etc

where a is an angle in degrees starting at 0 and increasing to 3 x 360
= 1080. Then I used the 'Radar' option in Chart. But I'm darned if I
can get the sort of result I want. Maybe I should be using radians?
But I thought it was likely others had already done this, so rather
than reinvent wheel...

Even better, if anyone has a finished spiral that is importable into
Word, then I'd be delighted to bypass the Excel stage altogether.

--
Terry, West Sussex, UK

andy

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Jun 26, 2003, 7:00:36 AM6/26/03
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Terry

As you say, why reinvent the wheel!! Go to Google (Images tab) and search
for spiral. There are hundreds. One should be right for your job.

Andy.

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Terry Pinnell

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Jun 26, 2003, 7:25:41 AM6/26/03
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Terry Pinnell <terrypi...@dial.pipexTHIS.com> wrote:

Well, I sorted my requirement by googling for a spiral image and
editing it in PaintShop Pro. But I'm still interested in seeing an
Excel formula so that I can roll my own.

andy

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Jun 26, 2003, 7:33:59 AM6/26/03
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Terry

So, you don't actually need it now!! You're just making up difficult tasks
to see how clever the group is!!

Andy

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Brian Clacher

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Jun 26, 2003, 7:35:34 AM6/26/03
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Use an XY chart and calculate the X and Y coords using:
x =a^n*Cos[a]
y=a^n*Sin[a]

probably n could be 1 so
x =a*Cos[a]
y=a*Sin[a]

would do.

Brian Clacher
http://xlschool.com

===================================

"Terry Pinnell" <terrypi...@dial.pipexTHIS.com> wrote in message

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Terry Pinnell

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Jun 27, 2003, 11:13:03 AM6/27/03
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"Brian Clacher" <Br...@XLschool.com> wrote:

>Use an XY chart and calculate the X and Y coords using:
>x =a^n*Cos[a]
>y=a^n*Sin[a]
>
>probably n could be 1 so
>x =a*Cos[a]
>y=a*Sin[a]
>
>would do.
>
>Brian Clacher
>http://xlschool.com
>

Thanks, but I think that's an ellipse!

Brian Clacher

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Jun 28, 2003, 7:49:33 AM6/28/03
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only if n = 0, have a look at :
http://xlschool.com/Articles/ExcelFiles/spiral.xls

Brian Clacher
http://xlschool.com

==========================================================


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Terry Pinnell

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Jun 29, 2003, 1:15:58 AM6/29/03
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"Brian Clacher" <Br...@XLschool.com> wrote:

Of course, sorry, my mistake.

Thanks for your help.

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