(a) As with exercise 4(b) above,

      x       3480 km
  -------- = ---------  so x = (3480 * 57.3)/384000 = 0.52 deg of arc.
  57.3 deg   384000 km

(b) Exercise left to the reader.

(c) As with Part (a) above,

      x      1.39 * 106 km
  -------- = -------------   so x = 0.53 deg of arc.
  57.3 deg   1.50 * 108 km

(d) The Moon and the Sun are almost exactly the same angular size on the sky.  
Thus, if the Moon moved directly between Earth and the Sun, the resulting eclipse 
could be quite beautiful.