How can i create a code which accept the 'peaks' of a quadrilateral and then give me the area of it?(without polyarea)

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Panagiotis Antaloglou 2020-5-30

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评论： David Hill 2020-6-8

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David Hill 2020-5-30

What do you mean by the peaks? Are you talking about the vertices?

Panagiotis Antaloglou 2020-5-30

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yes

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Answer 1

Adam Danz 2020-5-30

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编辑：Adam Danz 2020-6-8

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Follow this algorithm. There's a link toward the top of that page that shows how to implement the algorithm in JavaScript. Incidentally, polyarea also uses this algorithm but in vectorized format.

https://www.mathopenref.com/coordpolygonarea.html

verts = [
    1 1;
    4 1;
    4 2;
    1 2;
    ];
area = 0;   % Accumulates area
j = size(verts,1);
for i = 1 : j
    area =  (verts(j,1)+verts(i,1)) * (verts(j,2)-verts(i,2)) + area; 
    j = i;  
end
finalArea = abs(area/2); 

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Answer 2

David Hill 2020-5-31

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I would use the polyshape function or polyarea function

pgon=polyshape([0 2 1 2],[0 2 0 -2]);
a=area(pgon);
plot(pgon);

If you just want the area, then:

a=polyarea([0 2 1 2],[0 2 0 -2]);

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David Hill 2020-6-8

Must be homework if you do not want to use polyarea. What have you tried? I would use Heron's formula for the area of a triangle and add the two triangle areas.

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