theorem
  |.exp((th*<i>)).| = 1 &
  for th being Real holds |.sin th.| <= 1 & |.cos th.| <= 1
proof
  thus |.exp((th*<i>)).| =|.Sum((th*<i>) ExpSeq ).| by Def14
    .=1 by Lm5;
  let th be Real;
  thus |.sin(th).| <= 1 by Lm5;
  thus thesis by Lm5;
end;
