reserve x,y for Real;
reserve z,z1,z2 for Complex;
reserve n for Element of NAT;

theorem Th9:
  -sinh_C/.z = sinh_C/.(-z)
proof
  sinh_C/.(-z) = (exp(-z) - exp(-(-z)))/2 by Def3
    .= -(exp(z) - exp(-z))/2;
  hence thesis by Def3;
end;
