code: def rot_x(V, alpha):
      cosa, sina = np.cos(alpha), np.sin(alpha)
      M1 = np.array(
          [
              [1, 0, 0, 0],
              [0, cosa, -sina, 0],
              [0, sina, cosa, 0],
              [0, 0, 0, 1],
          ]
      )
      return np.dot(M1, V)
  
imports: import numpy
  from matplotlib import _api
label_desc: Use image node_id 21 for calling a global function with example usage: rot_x(V, alpha) and returns: np