title: What is a formula to get a vector perpendicular to another vector?
body: <p>What is a formula to get a three dimensional vector B lying on the plane perpendicular to a vector A?</p>
  
  <p>That is, given a vector A, what is a formula f(angle,modulus) which gives a vector that is perpendicular to A, with said modulus and rotated through an angle?</p>