code: def _calc_angle(p1, vertex, p2):
      x1, y1 = p1[0]
      xv, yv = vertex[0]
      x2, y2 = p2[0]
      a = ((xv - x2) * (xv - x2) + (yv - y2) * (yv - y2)) ** 0.5
      b = ((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)) ** 0.5
      c = ((x1 - xv) * (x1 - xv) + (y1 - yv) * (y1 - yv)) ** 0.5
      return math.degrees(
          math.acos((b**2 - a**2 - c**2) / (-2 * a * c))
      )
  
file_path: PaddleSeg/EISeg/eiseg/util/regularization/rs_regularization.py
imports: import math
  import cv2
  import numpy
  from .utils import calc_distance
label_desc: Use image node_id 6 for calling a global function with example usage: _calc_angle(p1, vertex, p2) and returns: math