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MathGroup Archive 2003

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Re: How to increase area of irregular polygon?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39291] Re: How to increase area of irregular polygon?
  • From: Steve Gray <stevebg at adelphia.net>
  • Date: Sun, 9 Feb 2003 04:51:14 -0500 (EST)
  • References: <b22jl4$65b$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On Sat, 8 Feb 2003 09:46:12 +0000 (UTC), "John Ng" <johnn at sfu.ca>
wrote:

>Hi,
>
>I wish to know how to increase an irregular polygon's area by, say, 10%.
>How would I go about doing that?  For example, if I have a set of (x,y)
>coordinates and figured out an area from that and I get an area X, how would
>I increase the polygon's area by X + 10% ?  In other words, if X = 100, I
>wish to know how to increase X to 110.
>
>The area of a polygon is defined as: a = 1/2 *
>((x1+x2)(y1-y2)+(x2+x3)(y2-y3)+...+(xn+x1)(yn-y1)).  Is this correct?
>
>Thanks for your help..

Gray:
	Can't you just multiply all coordinates by Sqrt[1.1]? This
will move the polygon as well as enlarge it, but that could be fixed.



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