Q:  What is the distance to Procyon?

                   1
          d  =  ----------    =  3.50 pc
                0.286 arcsec


  Q:  What is the linear size of the semi-major axis?
      Express your answer in Astronomical Units (AU).


          a  =  (theta in arcsec)  *  (d in pc)

             =  (4.1 arcsec)       *  (3.50 pc)

             =   14 AU


          (You can also convert all units to meters and
           degrees, compute the linear size of the semi-major
           axis in meters, then convert back to AU at the end)