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-   -   Calculating area from perimeter (https://www.askmehelpdesk.com/showthread.php?t=304829)

  • Jan 17, 2009, 11:12 AM
    ggg320
    Calculating area from perimeter
    Hi,
    I'd like to buy a home; I know the area according to the official records but I'd like to double-check by measuring the actual area. I walked along the perimeter of the land and it equals 452 meters. The shape of the land does not resemble any frequantly used geometrical figures; very superficially saying it's like a trapezium. This is why I'd like to find out if it's possible to calculate area by knowing a perimeter.
    Many thanks!
  • Jan 18, 2009, 10:49 AM
    galactus
    We need the angles at each corner as well as the distance between them. This should be on the deed.
  • Jan 19, 2009, 03:30 AM
    ROLCAM

    You need to tell us :-
    1) What are the four different lengths that make up the 452 metres.
    2) We need one more measurement that is the connecting length of two opposite corners.

    Then you can proceed:-
    Divide the trapezium into two triangles.
    You will finish up with two triangles with unequal sides.
    We can calculate the area of any triangle
    with unequal sides.
    The formula if you do not know it is:-

    The square root of:
    s ( s - a) (s -b) ( s - c).
    where s = the sum of the three sides a + b + c

    Having got the areas of the two triangles you
    then add the two up.

    Thus you get the area of the trapezium.

    rolcam.
  • Jan 20, 2009, 08:23 PM
    harum

    Try Google Earth. Perimeter length will still be useful, even though not necessary. There are programs around that calculate distances using Google maps. Should more than enough to get what you want.
  • Jan 20, 2009, 08:36 PM
    galactus
    Wow, that's a good idea. I did not know Google earth done that. Does the free version do that or do you have to pay?
  • Jan 21, 2009, 09:51 AM
    harum

    Well, it was all free for me; I guess you don't need fancy features for the basic stuff. Some metropolitan areas are mapped better than other in Google Earth, but Google Maps should be more than enough for that kind of project in most of the places. E.g. as a New Year resolution and using Google Maps, I have selected a four mile loop through neighborhood streets for jogging. Didn't go farther than that though.

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