How can you determine if you are in the blind spot of a large vehicle?

• It’s impossible to know; you can never be sure.
• If you cannot see both of the large vehicle’s side mirrors, you are too close.
  Explanation:

  "Large vehicles have significant blind spots, especially directly behind them. If you are driving behind a large vehicle and cannot see both of its side mirrors, you are likely in its blind spot and too close."
• If you can see both of the large vehicle’s side mirrors, you are too close.
• If you cannot see both sides of the large vehicle, you are too close.