title: Why is weight vector orthogonal to decision plane in neural networks
body: <p>I am beginner in neural networks. I am learning about perceptrons.
  My question is Why is weight vector perpendicular to decision boundary(Hyperplane)?
  I referred many books but all are mentioning that weight vector is perpendicular to decision boundary but none are saying why?</p>
  
  <p>Can anyone give me an explanation or reference to a book?</p>