code: def triangle_area(pt1, pt2, pt3):
      r
      a = 0.0
  
      a += pt1[0] * pt2[1] - pt2[0] * pt1[1]
      a += pt2[0] * pt3[1] - pt3[0] * pt2[1]
      a += pt3[0] * pt1[1] - pt1[0] * pt3[1]
  
      return abs(a) / 2
docs: r"""Return the area of a triangle.
  
      Parameters
      ----------
      pt1: (X,Y) ndarray
          Starting vertex of a triangle
      pt2: (X,Y) ndarray
          Second vertex of a triangle
      pt3: (X,Y) ndarray
          Ending vertex of a triangle
  
      Returns
      -------
      area: float
          Area of the given triangle.