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#1 2012-10-21 23:44:53
- Ronald
- Guest
Geometry
Regular polygon's area can be calculated,other polygon's area can also be calculated using graph coordinates,but i have heard that polygon's area can be calculated using sides and external angles is it true?if it is what is the method?
#2 2012-10-22 00:42:54
- bobbym
- Administrator
Online
Re: Geometry
Hi;
See if you can get what you need from here:
http://www.mathwords.com/a/area_regular_polygon.htm
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#3 2012-10-22 00:59:48
- Ronald
- Guest
Re: Geometry
No,i have heard that there is a formula for irregular polygon's area too(using side lengths and exterior angles
#4 2012-10-22 01:13:20
- bobbym
- Administrator
Online
Re: Geometry
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#5 2012-10-22 01:19:18
- zetafunc.
- Guest
Re: Geometry
If you know what the polygon looks like, you can just split it up into triangles and use Heron's formula. If you have the right angles you can then apply things like the sine rule, cosine rule, etc. to find all the sides of the triangles you have split the polygon into.
#6 2012-10-22 01:33:05
- Ronald
- Guest
Re: Geometry
The second link's 3rd method was the one I was looking for ,thank you.
#7 2012-10-22 01:34:25
- zetafunc.
- Guest
Re: Geometry
Wow, that third method is really useful. And you really do only need the side lengths and angles!
#8 2012-10-22 01:36:17
- bobbym
- Administrator
Online
Re: Geometry
Hi Ronald;
You are welcome.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#9 2012-10-22 02:34:12
- bob bundy
- Moderator
Offline
Re: Geometry
hi Ronald,
I like to make pictures that simplfy problems.
If you have the coordinates of the points you can always box in and make triangles and rectangles.
area of polygon = area of box less the bits you have over. see picture for example.
Bob
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei