Question 1154678
.
<pre>

By the way, there is another elementary method calculating the area of a polygon.


Place it into a rectangle with vertical and horizontal sides.


Make this rectangle as small as possible, i.e. get the polygon "inscribed" into the rectangle.


Calculate the area of the rectangle (which is easy).


Then subtract the areas of all excessive triangles, by "cutting" them.


It is very easy, too.


Doing in this way, you will get the answer.
</pre>