docs: def compute_expansion_alignment(satz_a, satz_b, satz_c, satz_d):
      """All angles in radians."""
      zeta_a = satz_a
      zeta_b = satz_b
  
      phi_a = compute_phi(zeta_a)
      phi_b = compute_phi(zeta_b)
      theta_a = compute_theta(zeta_a, phi_a)
      theta_b = compute_theta(zeta_b, phi_b)
      phi = (phi_a + phi_b) / 2
      zeta = compute_zeta(phi)
      theta = compute_theta(zeta, phi)
  
      c_expansion = 4 * (((theta_a + theta_b) / 2 - theta) / (theta_a - theta_b))
  
      sin_beta_2 = scan_width / (2 * H)
  
      d = ((R + H) / R * np.cos(phi) - np.cos(zeta)) * sin_beta_2
      e = np.cos(zeta) - np.sqrt(np.cos(zeta) ** 2 - d ** 2)
  
      c_alignment = 4 * e * np.sin(zeta) / (theta_a - theta_b)
  
      return c_expansion, c_alignment