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Map Making- Hypothetical Example




Click here to go to the map making topic's first page. (You should read that page before attempting the following.)


A hypothetical group of people went out into a hypothetical field, and noted the following, in order to make a map of the field.

The field looked a bit like this, and the corners, rather conveniently, came with the following "names".

sketch of field

The people measured the following angles:

With that information, and the ideas set out on the first page of this, you can draw a map of the field! It may help you to know that a piece of A4 or 8-1/2" x 11" paper will do fine. Turn it portrait- wise. (Not landscape. In other words, have the short edge nearest you.), Put 'A' about 3cm from the top left corner. Put 'B' 18cm below 'A'. (These points can be anywhere on the page... but if you put them in the 'wrong' places, you'll need a bigger piece of paper if you are going to get everything in.)

Once you have drawn all the lines implied by the angles above, you should get an 'L' shaped field. Don't worry if it isn't 'exactly' right.... just do what the numbers tell you to do!

Now... if it were a perfect world, you would have a perfect map. But the world isn't perfect. Therefore, scientists and engineers look for ways to check their work, ways to spot errors, ways to make results more nearly perfect.

The map makers went back to the field. The went to a place half way between A and B. Because it was half way between A and B, it was easy to mark it's correct position on the map they were making. They called this place G. They then collected the following measurements:

Draw those angles in on your map. IF.....

By measuring more angles than they 'must', map makers collect information which will check the accuracy of the map they are drawing.

Now.... have you really done what you should, according to the instructions above? There are two 'tricks' in this page's information which will help you see. When you are sure, sure, sure that you have done everything properly, click here to see what the 'tricks' were.


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