Calculate area of a object in cartesian plane

Question

I wonder if someone can help me to find the area of a 2-D object in Cartesian plane , when we know coordinates of every points. Eg : I want to calculate the area of a triangular. A(12,34) B(45,89) C(25,35)

I want a common algorithm to find any 2-D object's area.

Thank you.

Answer 1

Here you go, uses triangulation. This was literally the top result off Google when I searched "area of polygon given set of points". Please do your research before posting.