 the arguments of
  individual <tt>sin</tt>'s or <tt>cos</tt>'s.  For example, <tt>
    trigexpand(sin(x+y))</tt> gives <tt>cos(x) sin(y) + sin(x) cos(y)</tt>.</dd>
 <dt><b><tt>trigreduce(a)</tt></b></dt>
	<dd> Is a trig simplification function which
  uses trig identities to convert products and powers of <tt>sin</tt> and
  <tt>cos</tt> into a sum of terms, each of which contains only a single
  <tt>sin</tt> or <tt>cos</tt>.  For example, <tt>trigreduce(sin(x)^2)</tt>
  gives <tt>(1 - cos(2x))/2</tt>.</dd>