1.  12.43 cm
  2.  5.97o
  3.  690 cm

  1. Minimum height = 30 cm.
     Maximum height = 30 sqrt(2)
     30 sqrt(2) - 30 = 12.426 cm.

  2. Greatest angle occurs when front wheel centre is at maximum
      height and rear wheel centre at minimum height.
     Now sin p = 7/120. So p = 3.344o
     and sin q = (30 sqrt(2) - 23)/120. So q = 9.316o
     The cross-bar turns through the same angle as the line of
      centres, and q - p = 5.972o
   (Several erroneous methods give answers quite close to the correct value.
    So we accept only answers within 0.01o of this value.)

  3. Distance must be a multiple of 46 cm and an odd multiple of 30 cm.
     By inspection, this first occurs when distance = 690 cm.