code: public static float fieldOfView(float focalLength, float sensorWidth) {
          double fov = 2 * Math.atan(.5 * sensorWidth / focalLength);
          return (float) Math.toDegrees(fov);
      }
docs: Calculate the FOV of camera, using focalLength and sensorWidth
  @param focalLength
  @param sensorWidth
  @return FOV