how i can calculate the surface(2D) of delaunay triangulation ??????????????????

I want to calculate the area(the surface) of a zone(2D) using the delaunay triangulation or convex hull, how can i do ?plzzzzzzzz i need help net = [1:n;rand([1,n])*x;rand([1,n])*y]; net1 = net; xx=net(2,:); yy=net(3,:); dt = DelaunayTri(xx',yy'); P = [xx',yy']; K = convexHull(dt); triplot(dt,'cyan');