Calculate Triangle Area from Three Coordinate Points

You are given points, which contains exactly three points, each represented by an integer coordinate pair. Your task is to find the area of the triangle whose vertices are those three points. Your solution must use a mathematical formula, and be ready to explain the intermediate steps of the calculation; the program itself prints only the area as a number. All coordinates are integers. Example Input: Example Output: Constraints: $$0 \le x_i, y_i \le 100$$ Examples Example