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.