[Edu-sig] python fun geometry

[Vern Ceder]

On Thu, Sep 16, 2010 at 1:46 PM, roberto <roberto03 at gmail.com> wrote:

> Now, i have a geometric question about what the authors write:
> in sec 1.1.2 they say that the following logo code:
>
> TO ARCR R DEG
>            REPEAT DEG
>                  FORWARD R
>                  RIGHT 1
>
> produce a circular arc as output, having "DEG" degrees and "R" radius;
> and that it's true, actually;
> if DEG = 180 the arc is a semicircumference and so on...
>
> But, the "R" in the code is the single step forward the turtle does in
> its path so i can't understand how this R can be seen as the radius of
> the circular arc.
> Any hint is very appreciated.
>

Going forward 1 pixel and then turning 1 degree (and then repeating 360
times) gives you as close to a circle as you can get on the screen. If you
were go to forward 2 pixels, the circle will be less smooth, but the radius
will be twice the size... and so on...

HTH,

Vern




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> roberto
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-- 
This time for sure!
   -Bullwinkle J. Moose
-----------------------------
Vern Ceder, Director of Technology
Canterbury School, 3210 Smith Road, Ft Wayne, IN 46804
vceder at canterburyschool.org; 260-436-0746; FAX: 260-436-5137

The Quick Python Book, 2nd Ed - http://bit.ly/bRsWDW
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