theorem Th62:
  @(spiral_of_fifths(MS,frequency,frequency).2) /
  @frequency = (3 * 3 qua Real) / (2 * 2 * 2)
  proof
    @(spiral_of_fifths(MS,frequency,frequency).2) /
    @frequency = ((9 qua Real) / 8 * @frequency) / @frequency by Th59
              .= (3 * 3 qua Real) / (2 * 2 * 2) by XCMPLX_1:89;
    hence thesis;
  end;
