Finding segmented triangle area of polygon

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SeungHyun Cha on 9 Jun 2020
Commented: SeungHyun Cha on 14 Jun 2020
I tried to find out the triangle area in the polygon based on determinant theory.
Here is the reference I tried to calculate the area of triangles using indeces: function and for-loop.
function area = trianglearea(a)
for i = 2 : length(i)-1;
tri = [a(1,1), a(1,i), a(1,i+1); a(2,1), a(2,i), a(2,i+1); 1, 1, 1];
area = 0.5*det(tri)
end
end
A = [0 10 12 8 6 0; 0 1 4 6 8 0];
trianglearea(A)
then the results is and workplace is the results of area of triangles do not show each reasults following different i value in for-loop. It just show the final result when i = lengh(a)-1.
How can I display every triangle area..?

Chidvi Modala on 12 Jun 2020
You can make use of the following code to capture the area of each triangle and also to find the area of entire polygon
function [area, totalArea] = trianglearea(a)
area = zeros(length(a)-2,1);
for i = 1 : length(area)
tri = [a(1,1), a(1,i+1), a(1,i+2); a(2,1), a(2,i+1), a(2,i+2); 1, 1, 1];
area(i) = 0.5*det(tri);
end
totalArea = sum(area); % Total Area of polygon
end
SeungHyun Cha on 14 Jun 2020
Thank you

Image Analyst on 12 Jun 2020
Or simply use polyarea().
SeungHyun Cha on 14 Jun 2020
Thank you